[chore] updates code.superseriousbusiness.org/oauth2/v4 to ssb-v4.5.3-1 (#4245)

A brief note on the above change: Go does not seem to like version tagging outside of `v?[0-9\.]` formatting, so it translates `ssb-v4.5.3-1` to `v4.5.4-0.20250606121655-9d54ef189d42` and as such sees it as a "downgrade" compared to the previous `v4.9.0`. which functionally isn't a problem, everything still behaves as it should, but it means people can't just run `go get repo@latest` for this particular dependency.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4245
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>

vendor/code.superseriousbusiness.org/oauth2/v4/.travis.yml

@@ -0,0 +1,13 @@
+language: go
+sudo: false
+go_import_path: github.com/go-oauth2/oauth2/v4
+go:
+  - 1.13
+before_install:
+  - go get -t -v ./...
+
+script:
+  - chmod +x ./go.test.sh && ./go.test.sh
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)