fix: avoid grep -P for version extraction in release workflow

The android runner's grep lacks PCRE support, so grep -oP failed
silently inside command substitution, leaving VERSION_CODE/NAME
empty and breaking the changelog lookup. Use plain bash parameter
expansion instead.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.forgejo/workflows/release.yml

@@ -14,8 +14,8 @@ jobs:
       - name: Extract version
         run: |
           VERSION=$(grep '^version:' pubspec.yaml | sed 's/version: //')
-          echo "VERSION_CODE=$(echo "$VERSION" | grep -oP '(?<=\+)\d+')" >> $GITHUB_ENV
-          echo "VERSION_NAME=$(echo "$VERSION" | grep -oP '^[^+]+')" >> $GITHUB_ENV
+          echo "VERSION_CODE=${VERSION##*+}" >> $GITHUB_ENV
+          echo "VERSION_NAME=${VERSION%%+*}" >> $GITHUB_ENV
 
       - name: Decode keystore
         run: |