ci: Fix GH actions version

Use v4 as older ones are deprecated.

Signed-off-by: Chaitanya Tata <[email protected]>

Author: krish2718

.github/workflows/compliance.yml

@@ -8,14 +8,14 @@ jobs:
     name: Run compliance checks on patch series (PR)
     steps:
     - name: Checkout the code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
       with:
         path: ncs/nrfxlib
         ref: ${{ github.event.pull_request.head.sha }}
         fetch-depth: 0
 
     - name: cache-pip
-      uses: actions/cache@v1
+      uses: actions/cache@v4
       with:
         path: ~/.cache/pip
         key: ${{ runner.os }}-doc-pip