[CI]: set IS_BETA for xcodebuild to build beta IPA with commit id as MARKETING_VERSION

.github/workflows/rebase.yml

@@ -116,7 +116,10 @@ jobs:
           echo ">>>>>>>>> Xcode-Derived-Data <<<<<<<<<<"
           ls -la ~/Library/Developer/Xcode/DerivedData || true  # List contents if directory exists    
           echo ""
-  
+
+      - name: Set current build as BETA
+        run: echo "IS_BETA=1" >> $GITHUB_ENV
+        
       - name: Build SideStore
         run: make build | xcpretty && exit ${PIPESTATUS[0]}