fix(deps): update dependency superagent to v5

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
superagent	dependencies	major	3.8.3 -> 5.1.0

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Release Notes

visionmedia/superagent

v5.1.0

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• Disable setting default user-agent (#​1495) e652b8c

v5.0.9

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• feat: added fast-safe-stringify instead of JSON.stringify (closes #​1464) 2e5d6fd

v5.0.8

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• fix: removed @​babel/transform-runtime (closes #​1494) 28e7101

v5.0.6

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• feat: bump deps, fixed lint issues a3f75ed
• fix: omit queries that are set to undefined (#​1486) 7942c2d

v5.0.5

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• fix: remove redundant defs, bump deps fcf6cff

v5.0.4

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• Invalid redirect in pipe (#​1471) 7d0ea4b
• docs: fixed missing polyfill 251a1cb
• fix: amilajack/eslint-plugin-compat#​224 2d81605

v5.0.3

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• fix: add browser compiled version to lib folder (#​1470) 14acecd
• Revert "Avoiding to set the "Content-Length" header for GET requests (#​1460)" (#​1477) fe8d902
• Avoiding to set the "Content-Length" header for GET requests (#​1460) 804c35c

v5.0.2

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• fix: fixed browser require for webpack (closes #​1474) ccc7f56

v4.1.0

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• .connect() IP/DNS override option (Kornel)
• .trustLocalhost() option for allowing broken HTTPS on localhost
• .abort() used with promises rejects the promise.

v4.0.0

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Breaking changes

• Node.js v4 has reached it's end of life, so we no longer support it. It's v6+ or later. We recommend Node.js 10.
• We now use ES6 in the browser code, too.
  • If you're using Browserify or Webpack to package code for Internet Explorer, you will also have to use Babel.
  • The pre-built node_modules/superagent.js is still ES5-compatible.
• .end(…) returns undefined instead of the request. If you need the request object after calling .end() (and you probably don't), save it in a variable and call request.end(…). Consider not using .end() at all, and migrating to promises by calling .then() instead.
• In Node, responses with unknown MIME type are buffered by default. To get old behavior, if you use custom unbuffered parsers, add .buffer(false) to requests or set superagent.buffer[yourMimeType] = false.
• Invalid uses of .pipe() throw.

Minor changes

• Throw if req.abort().end() is called
• Throw if using unsupported mix of send and field
• Reject .end() promise on all error events (Kornel Lesiński)
• Set https.servername from the Host header (Kornel Lesiński)
• Leave backticks unencoded in query strings where possible (Ethan Resnick)
• Update node-mime to 2.x (Alexey Kucherenko)
• Allow default buffer settings based on response-type (shrey)
• response.buffered is more accurate.

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[matticbot]

Test live: https://calypso.live/?branch=renovate/superagent-5.x

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[blowery]

@sgomes would you mind taking this for a spin? You're more familiar with how we use superagent than I am.

[sgomes]

@sgomes would you mind taking this for a spin? You're more familiar with how we use superagent than I am.

I removed all of the usage I was familiar with! 😄 What's left is server-side usage only.

I'll take a look and see what I can find!

[sgomes]

@blowery Looks like we're going to have duplicate versions of superagent unless we update wpcom-xhr-request too 😞 Perhaps we should prioritise bringing wpcom and wpcom-xhr-request into the monorepo, in order to modernise them?

[scinos]

This is ready for a re-review.

[sgomes]

Note: superagent has been removed entirely from the client-side, so this should only affect the server-side now.

[sgomes]

Have we tested that things work correctly after this change? Looking at version release notes, I see a few possible breaking changes when going from v3 to v4:

• .end(…) returns undefined instead of the request.
• In Node, responses with unknown MIME type are buffered by default.

With v5, it looks like the authors decided it wasn't worth it to write proper release notes, so it's harder to tell where the breaking changes are 😬