Remove useless code; distros checked are not in use anymore

.github/workflows/main.yml

@@ -47,15 +47,6 @@ jobs:
     # Fetch tags to determine proper version number inside git
     - name: fetch tags
       run: git fetch --tags
-      # We cannot pull tags with old distros, since there is no `.git`. See below.
-      if: "! (matrix.distro == 'ubuntu-bionic' || matrix.distro == 'ubuntu-xenial' || matrix.distro == 'debian-stretch')"
-
-    # The Github checkout Action doesn't support distros with git older than 2.18
-    # With git<2.18 it downloads the code via API and does not clone it via git :facepalm:
-    # To succeed the tests, we have to manually replace the VERSION macro
-    - name: fix version number for old distros
-      run: 'sed -i "s/-non-git/-ci-oldgit-$GITHUB_SHA/" Makefile'
-      if: "  (matrix.distro == 'ubuntu-bionic' || matrix.distro == 'ubuntu-xenial' || matrix.distro == 'debian-stretch')"
 
     - name: build
       run: make -j all dunstify test/test