build: Bump httpmock from 0.6.8 to 0.7.0 in /backend

Bumps [httpmock](https://github.com/alexliesenfeld/httpmock) from 0.6.8 to 0.7.0.
- [Release notes](https://github.com/alexliesenfeld/httpmock/releases)
- [Changelog](https://github.com/alexliesenfeld/httpmock/blob/master/CHANGELOG.md)
- [Commits](alexliesenfeld/httpmock@v0.6.8...v0.7.0)

---
updated-dependencies:
- dependency-name: httpmock
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

backend/Cargo.lock

@@ -69,7 +69,7 @@ rdkafka = { version = "0.36.2", features = [
 
 [dev-dependencies]
 mockall = "0.11.4"
-httpmock = "0.6"
+httpmock = "0.7"
 once_cell = "1.18.0"
 
 [features]