Update CONTRIBUTING.md and PULL_REQUEST_TEMPLATE.md to show 'gradlew test' instead of 'mvn test' (Fixes #2081)

Author: metaprime

.github/PULL_REQUEST_TEMPLATE.md

@@ -16,7 +16,7 @@ Please add details about your change here.
 # Testing
 
 Required verification:
-* [ ] I've verified that there are no regressions in `mvn test` (there are no new failures or errors).
+* [ ] I've verified that there are no regressions in `gradlew test` (there are no new failures or errors).
 * [ ] I've verified that this change works as intended.
   * [ ] Downloads all relevant content.
   * [ ] Downloads content from multiple pages (as necessary or appropriate).

CONTRIBUTING.md

@@ -57,7 +57,7 @@ Before you open your pull request, please consider the following:
 * Please ensure your change includes only the minimum changes needed to fix a single issue. These are easiest to review and tend to get merged more quickly. If the scope of your PR is wider than a single issue, you may be asked to reopen your PR as multiple separate PRs.
 * Are you fixing an issue from one of the issue trackers ([RipMeApp](https://github.com/RipMeApp/ripme/issues) or ([RipMeApp2](https://github.com/RipMeApp2/ripme/issues) or [4pr0n](https://github.com/4pr0n/ripme/issues))? If so, please ensure that you reference the issue you are fixing in your commit message so that it will be [automatically closed](https://help.github.com/articles/closing-issues-via-commit-messages/).
 * Please ensure you verify that you did not break any functionality outside of your change or feature
-  * The CI might be broken, so please ensure that `mvn test` shows no new errors since before your change.
+  * The CI might be broken, so please ensure that `gradlew test` shows no new errors since before your change.
   * Keep in mind each Ripper likely supports multiple URL formats for each website, which have different content layouts (users, galleries, etc.)
   * We deal with live websites, so things might break while we aren't looking. Websites can change and content can be deleted at any time. Our code and/or tests may need to be rewritten to fix issues.
 * Please consider adding a test to check for regressions to the Ripper you added or the bug you fixed.