Fix Windows CI: use bash shell for git submodule commands

On Windows MSYS2 runners, the default shell is 'msys2' which doesn't
understand 'git submodule' commands the same way. Adding shell: bash
forces the step to use bash, which properly executes git and finds
submodule content.

Affected jobs: build-windows-qt, build-windows-daemon

.github/workflows/build-all.yml

@@ -106,6 +106,7 @@ jobs:
 
       - name: Init submodules
         run: git submodule update --init --recursive
+        shell: bash
 
       - uses: msys2/setup-msys2@v2
         with:
@@ -263,6 +264,7 @@ jobs:
 
       - name: Init submodules
         run: git submodule update --init --recursive
+        shell: bash
 
       - uses: msys2/setup-msys2@v2
         with: