CI: Ensure finding no pattern match results in an empty string

If no pattern match is found, which we expect for Qt x86 builds, then
return an empty string by enabling the nullglob option.

Additionally, add quotes for paths for safety and fix the for loop array
syntax.

.github/workflows/main.yaml

@@ -607,6 +607,7 @@ jobs:
         run: |
           : Package Windows dependencies
           shopt -s extglob
+          shopt -s nullglob
 
           for arch in x64 x86; do
             _temp=$(mktemp -d)
@@ -624,8 +625,8 @@ jobs:
             mv windows-deps-${{ steps.metadata.outputs.version }}-${arch}.zip ${GITHUB_WORKSPACE}
 
             files=("${GITHUB_WORKSPACE}"/qt6-windows-"${arch}"-!(*-@(Debug|RelWithDebInfo|Release|MinSizeRel))/*.zip)
-            for artifact in ${files}; do
-              mv ${artifact} ${GITHUB_WORKSPACE}
+            for artifact in "${files[@]}"; do
+              mv "${artifact}" "${GITHUB_WORKSPACE}"
             done
             popd > /dev/null
           done