CI: Set LC_ALL=C on build

In order to avoid sed error at regenerating translation files.

Author: ichizok

.github/workflows/ci-macvim.yaml

@@ -205,6 +205,8 @@ jobs:
           cat src/auto/config.h
 
       - name: Build
+        env:
+          LC_ALL: C
         run: |
           set -o verbose