ci(workflows): set explicit GITHUB_TOKEN permissions for compile_windows

CodeQL flagged the workflow for not constraining GITHUB_TOKEN. Limit it
to contents: read since the job only needs to checkout sources and
upload artifacts.

Signed-off-by: Nuno Marques <n.marques21@hotmail.com>

.github/workflows/compile_windows.yml

@@ -26,6 +26,9 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+permissions:
+  contents: read
+
 jobs:
   build:
     name: Windows SITL (${{ matrix.toolchain }})