Override fetch depth in actions/checkout

To check if our dependencies are up to date or not without spamming
the commit history, we diff from HEAD to the commit the dependency
points to. Hence, we need the commit history to decide wether to
go get the latest revision of the module.

.github/workflows/auto-updates.yaml

@@ -125,6 +125,8 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: main
+          fetch-depth: 0
+          # ^ 0 means infinity in this context. This is necessary to later be able to compute diffs.
       - name: Set up git
         uses: ./.github/actions/setup-git
         with: