test don't use homebrew iconv

Author: ychin

.github/workflows/macvim-buildtest.yaml

@@ -232,8 +232,10 @@ jobs:
             sed -i.bak -f ci/config.mk.optimized.sed src/auto/config.mk
           fi
 
-          # Use Homebrew GNU libiconv since Apple iconv has been broken since macOS 14
-          sed -i.bak -f ci/config.mk.brew-libiconv.sed src/auto/config.mk
+          if ${{ inputs.publish == true }}; then
+            # Use Homebrew GNU libiconv since Apple iconv has been broken since macOS 14
+            sed -i.bak -f ci/config.mk.brew-libiconv.sed src/auto/config.mk
+          fi
 
       - name: Modify configure result
         if: inputs.publish