Fix usage of coverage in GHA and bump version

.github/workflows/ci_poetry.yml

@@ -124,12 +124,14 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - run: pipx install poetry==1.8.2
+      - run: poetry config virtualenvs.in-project true
       - uses: actions/setup-python@v5
         with:
           python-version: "3.10"
 
       - name: Install dependencies
-        run: python -m pip install --upgrade coverage[toml]
+        run: poetry install --only dev
 
       - name: Download data
         uses: actions/download-artifact@v4
@@ -143,7 +145,7 @@ jobs:
         # We added this step to replace the variable `MERGE_COVERAGE_FILES: true`
         # in the next step, which had started to raise errors
         # (https://github.com/fractal-analytics-platform/fractal-server/pull/1725).
-        run: coverage combine coverage-data-*
+        run: poetry run coverage combine coverage-data-*
 
       - name: Add coverage comment to Pull Requests
         id: coverage_comment

CHANGELOG.md

@@ -3,6 +3,8 @@
 # Unreleased
 
 * Tests:
+    * Use locked version of `coverage` in GitHub action (\#882).
+    * Bump `coverage` version from 6.5 to 7.6 (\#882).
     * Skip `test_import_ome_zarr_image_BIA` (\#879).
 
 # 1.3.4