fix: use posix shell syntax for activation

Switched the virtual environment activation command to be compliant with POSIX shell syntax. The previous `source` command is replaced with `.`, making the script more broadly compatible with different shell environments without requiring bash specifically. This change ensures greater portability and compatibility of the release workflow across diverse CI/CD execution environments.

.forgejo/workflows/release.yml

@@ -25,7 +25,7 @@ jobs:
         run: |
           python3 -V
           python3 -m venv venv
-          source venv/bin/activate
+          . ./venv/bin/activate
           pip install -U pip
           pip install .[all]
 
@@ -46,7 +46,7 @@ jobs:
       - name: Set up Python environment
         run: |
           python3 -m venv venv
-          source venv/bin/activate
+          . ./venv/bin/activate
 
       - name: Install publishing tools
         run: |