ci: update GH workflow (coverage fix)

- Changed the runner environment from ubuntu-24.04 to ubuntu-latest for both tests and coverage jobs.
- Simplified the tox command to directly specify the environment.
- Adjusted the coverage data upload path to include the Python version.

Author: ekalinin

.github/workflows/main.yml

@@ -10,7 +10,7 @@ on:
 jobs:
   tests:
     name: Python ${{ matrix.python-version }}
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
 
     strategy:
       fail-fast: false
@@ -28,7 +28,6 @@ jobs:
     - uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
-        allow-prereleases: true
 
     - name: Install dependencies
       run: |
@@ -39,19 +38,21 @@ jobs:
 
     - name: Run tox targets for ${{ matrix.python-version }}
       run: |
-        ENV_PREFIX=$(tr -C -d "0-9" <<< "${{ matrix.python-version }}")
-        TOXENV=$(tox --listenvs | grep "^py$ENV_PREFIX" | tr '\n' ',') tox
+        tox -e py${{ matrix.python-version }}
+      env:
+          # Set the COVERAGE_FILE environment variable for coverage.py
+          COVERAGE_FILE: .coverage.${{ matrix.python-version }}
 
     - name: Upload coverage data
       if: always()
       uses: actions/upload-artifact@v6
       with:
         name: coverage-data-${{ matrix.python-version }}
-        path: '.coverage.*'
+        path: .coverage.${{ matrix.python-version }}
 
   coverage:
     name: Coverage
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     needs: tests
     steps:
       - uses: actions/checkout@v5
@@ -76,7 +77,6 @@ jobs:
           python -m coverage report --fail-under=55
 
       - name: Upload HTML report
-        if: ${{ failure() }}
         uses: actions/upload-artifact@v6
         with:
           name: html-report