Fix host diffing

Git treats the path as absolute whilst, at leas to my understanding, the
nix flake manual specifies that this ath can be relative. Thus
explicitly setting the current working directory as the path.

.github/scripts/diff-hosts.sh

@@ -1,6 +1,7 @@
 #!/usr/bin/env bash
 #
 debug="${ACTIONS_STEP_DEBUG-false}"
+set -x
 if $debug; then
   set -x
 else
@@ -41,14 +42,15 @@ fi
 
 before_rev="$(git rev-parse "$before_ref")"
 before_rev_abbr="$before_ref"
-before_flake="git+file:.?ref=${before_rev}"
+# Relative flake git flake urls don't work (right now?) because git treats the path as absolute
+before_flake="git+file:$(pwd)?rev=${before_rev}"
 
 after_rev="$(git rev-parse --verify HEAD)"
 after_rev_abbr="$(git rev-parse --abbrev-ref HEAD)"
 if [[ -z $(git status --short) ]]; then
     # If the working tree is clean, we can use the latest commit hash directly
     # and thus profit from even more reduced build times
-    after_flake="git+file:.?ref=${after_rev}"
+    after_flake="git+file:$(pwd)?rev=${after_rev}"
 else
     # That way the script can be used to check local (non commited) changes
     after_flake="."