Use powershell throughout

.github/workflows/build_windows.yaml

@@ -1,6 +1,11 @@
 # This workflow relies on actions/cache to store the hak dependency artifacts as they take a long time to build
 # Due to this extra care must be taken to only ever run all build_* scripts against the same branch to ensure
 # the correct cache scoping, and additional care must be taken to not run untrusted actions on the develop branch.
+
+# window-latest by default uses the pwsh shell which breaks codeSigningCert in the workflow
+defaults:
+  run:
+    shell: powershell
 on:
     workflow_call:
         secrets:
@@ -111,7 +116,6 @@ jobs:
 
             - name: Install and configure eSigner CKA
               if: inputs.sign
-              shell: powershell
               run: |
                   Set-StrictMode -Version 'Latest'