chore: change PHP version to 8.2 for coverage

To fix the following error:
-----
DatabaseLive (8.1, MySQLi, 8.0) / tests
Run actions/upload-artifact@v4
With the provided path, there will be 1 file uploaded
Artifact name is valid!
Root directory input is valid!
Error: Failed to CreateArtifact: Received non-retryable error: Failed request: (409) Conflict: an artifact with this name already exists on the workflow run
-----
Becaue "DatabaseLive (8.1, MySQLi, 5.7) / tests" already uploaded database-live-tests-php-8.1-db-MySQLi.

Author: kenjis

.github/workflows/test-phpunit.yml

@@ -47,7 +47,7 @@ jobs:
     steps:
       - id: coverage-php-version
         run: |
-          echo "version=8.1" >> $GITHUB_OUTPUT
+          echo "version=8.2" >> $GITHUB_OUTPUT
 
   sanity-tests:
     name: Others