ci(lint): do not fail linter on push events (#5331)

Previous behavior:
The following error was causing an exit 1 in GitHub Actions when a pushing
to the `main` branch

```
Error: Similar commit hashes detected: previous sha is equivalent to the
current sha
```

Expeceted behavior:
Allow the linter to run succesfully even if the previous SHA has no files
changed

Solution:
Add `fetch-depth: 2` to retrieve the preceding commit

.github/workflows/lint.yml

@@ -41,6 +41,7 @@ jobs:
         id: changed-files-rust
         uses: tj-actions/[email protected]
         with:
+          fetch-depth: 2
           files: |
             **/*.rs
             **/Cargo.toml
@@ -53,6 +54,7 @@ jobs:
         id: changed-files-workflows
         uses: tj-actions/[email protected]
         with:
+          fetch-depth: 2
           files: |
             .github/workflows/*.yml