ci - install git before actions/checkout step

If checkout is done before git is installed, the repo is not cloned
using git but downloaded over https, which results in the repo missing
its .git directory.

Author: sedmicha

.github/workflows/packages.yml

@@ -22,7 +22,6 @@ jobs:
     container: ${{ matrix.image }}
 
     steps:
-    - uses: actions/checkout@v2
     - name: Define variables
       uses: actions/github-script@v5
       with:
@@ -46,6 +45,9 @@ jobs:
       env:
         DEBIAN_FRONTEND: noninteractive
 
+    # Checkout repository --------------------------------------------------------------------
+    - uses: actions/checkout@v2
+
     # Build LIBFDS DEB package ---------------------------------------------------------------
     - name: Checkout libfds library - master branch
       if: github.ref == 'refs/heads/master'