Bump abatilo/actions-poetry from 2.4.0 to 4.0.0

Bumps [abatilo/actions-poetry](https://github.com/abatilo/actions-poetry) from 2.4.0 to 4.0.0.
- [Release notes](https://github.com/abatilo/actions-poetry/releases)
- [Changelog](https://github.com/abatilo/actions-poetry/blob/master/.releaserc)
- [Commits](abatilo/actions-poetry@v2.4.0...v4.0.0)

---
updated-dependencies:
- dependency-name: abatilo/actions-poetry
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/freeagent-gem.yml

@@ -19,7 +19,7 @@ jobs:
         with:
           python-version: "3.9"
       - name: Setup Poetry # Required for testing but not for building the gem.
-        uses: abatilo/actions-poetry@v2.4.0
+        uses: abatilo/actions-poetry@v4.0.0
         with:
           poetry-version: "1.1.13"
       - run: bundle install

.github/workflows/test.yml

@@ -14,7 +14,7 @@ jobs:
         with:
           python-version: "3.9"
       - name: Setup Poetry
-        uses: abatilo/actions-poetry@v2.4.0
+        uses: abatilo/actions-poetry@v4.0.0
         with:
           poetry-version: "1.1.13"
       - run: bundle install