gh-action: Set bash shell for bvt workflow

It's important for windows to fail correctly.
Further: actions/runner-images#6668

Signed-off-by: Tim Zhang <tim@hyper.sh>

Author: Tim-Zhang

.github/workflows/bvt.yml

@@ -29,6 +29,9 @@ jobs:
           make -C compiler
           make -C ttrpc-codegen
           make -C example build-examples
+        # It's important for windows to fail correctly
+        # https://github.com/actions/runner-images/issues/6668 
+        shell: bash
 
   deny:
     runs-on: ubuntu-latest