This updates Gitaly's latest Protocol Buffer definitions, which were
last updated in Feburary 2020, with the latest version of Gitaly. This
is needed to support a new flag (`IncludeLfsBlobs`) in the
`GetArchiveRequest` RPC.

Because we started tagging Gitaly versions `v13.x.x` instead of
`v1.x.x`, `go get` refuses to update the Gitaly module using the latest
tag or SHA (gitlab-org/gitaly#3177).  Go
tries to enforce semantic compatibility by requiring the use of module
paths (e.g. `m/v13`), and Gitaly doesn't adhere to this scheme.

To workaround this issue, we use the replace directive
(https://github.com/golang/go/wiki/Modules#when-should-i-use-the-replace-directive):

```
go mod edit -replace gitlab.com/gitlab-org/gitaly=gitlab.com/gitlab-org/gitaly@3f5e218def93024f3aafe590c22cd1b29f744105
```