Use shell: bash in check-autogen-diff

Author: MaxDesiatov

.github/workflows/main.yml

@@ -19,6 +19,7 @@ jobs:
         with:
           fetch-depth: 2
       - name: Run auto-generated code checks
+        shell: bash
         run: |
           test $(swift run -q --package-path Utilities WasmKitDevUtils wasmgen | wc -l) = "0"
           test $(swift run -q --package-path Utilities WasmKitDevUtils vmgen | wc -l) = "0"