remove support for page query params

[kmossco]

After we released v5.1.3 to add support for the cursor based pagination, this new version removes that support and will throw an error if the page pagination parameter is used.

[shortcut-integration]

This pull request has been linked to Shortcut Story #51957: [PHP] Add support for new pagination to client libs.

[codeclimate]

Code Climate has analyzed commit 1503f3a and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 75.5%.

View more on Code Climate.

[sbrych]

LGTM 👍🏻

[kmossco]

Merging this even with the coding guidelines failure, because I try to run it locally and I don't get the same error as in the action:

➜  chartmogul-php git:(sc-51957/deprecate_old_pagination) ./vendor/bin/php-cs-fixer check src/
Loaded config default.
Using cache file ".php-cs-fixer.cache".

Found 0 of 88 files that can be fixed in 0.001 seconds, 14.000 MB memory used
➜  chartmogul-php git:(sc-51957/deprecate_old_pagination) ./vendor/bin/php-cs-fixer check src/Http/Retry.php
Loaded config default.
Using cache file ".php-cs-fixer.cache".