Bump cache action dep version

Author: iamvery

.github/workflows/elixir.yml

@@ -25,7 +25,7 @@ jobs:
         elixir-version: '1.18.4' # Define the elixir version [required]
         otp-version: '28.0.2' # Define the OTP version [required]
     - name: Restore dependencies cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: deps
         key: ${{ runner.os }}-mix-${{ hashFiles('**/mix.lock') }}