[UPMERGE] 2.0 -> 2.1 (#420)

This PR has been generated automatically.
For more details see
[upmerge_pr.yaml](/Sylius/PayPalPlugin/blob/1.7/.github/workflows/upmerge_pr.yaml).

**Remember!** The upmerge should always be merged with using `Merge pull
request` button.

In case of conflicts, please resolve them manually with usign the
following commands:
```
git fetch upstream
gh pr checkout <this-pr-number>
git merge upstream/2.1 -m "Resolve conflicts between 2.0 and 2.1"
```

If you use other name for the upstream remote, please replace `upstream`
with the name of your remote pointing to the `Sylius/PayPalPlugin`
repository.

Once the conflicts are resolved, please run `git merge --continue` and
push the changes to this PR.

Author: NoResponseMate

.gitignore

@@ -1,4 +1,5 @@
 /vendor/
+/var/
 /node_modules/
 /composer.lock