Bump truffle from 5.1.30 to 5.1.31 (#863)

Bumps [truffle](https://github.com/trufflesuite/truffle) from 5.1.30 to 5.1.31.
- [Release notes](https://github.com/trufflesuite/truffle/releases)
- [Commits](https://github.com/trufflesuite/truffle/compare/truffle@5.1.30...truffle@5.1.31)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

package.json

@@ -110,7 +110,7 @@
     "solidity-bytes-utils": "0.0.8",
     "solidity-coverage": "^0.7.7",
     "solium": "^1.2.5",
-    "truffle": "^5.1.30",
+    "truffle": "^5.1.31",
     "truffle-assertions": "^0.9.2",
     "truffle-plugin-verify": "^0.3.11",
     "ts-node": "^8.10.2",

yarn.lock

@@ -8699,10 +8699,10 @@ truffle-plugin-verify@^0.3.11:
     querystring "0.2.0"
     sol-merger "3.0.1"
 
-truffle@^5.1.30:
-  version "5.1.30"
-  resolved "https://registry.yarnpkg.com/truffle/-/truffle-5.1.30.tgz#93d8fadfaf9ae58c05081569a026676d5f425364"
-  integrity sha512-wA88Ija0qO3ggzIEFMydg7FfxRqNRbYq1WVmb9Mdvx1D416RojRBotdML7KPH6T5lE6UKK8UeTalDTdG2KKqeQ==
+truffle@^5.1.31:
+  version "5.1.31"
+  resolved "https://registry.yarnpkg.com/truffle/-/truffle-5.1.31.tgz#fbf1416a2855442189d124c03343b7f8523dadf2"
+  integrity sha512-T9CJ90qInf+/rFxSLdF/nhTZNUV8cZx70iO0EsqXWm6ibcC5/dzRDDfl6FC/xLndpnKZIhs4RJL0TEG7rLohJg==
   dependencies:
     app-module-path "^2.2.0"
     mocha "5.2.0"