Bump github.com/hashicorp/go-retryablehttp from 0.7.7 to 0.7.8 in /test

Bumps [github.com/hashicorp/go-retryablehttp](https://github.com/hashicorp/go-retryablehttp) from 0.7.7 to 0.7.8.
- [Changelog](https://github.com/hashicorp/go-retryablehttp/blob/main/CHANGELOG.md)
- [Commits](hashicorp/go-retryablehttp@v0.7.7...v0.7.8)

---
updated-dependencies:
- dependency-name: github.com/hashicorp/go-retryablehttp
  dependency-version: 0.7.8
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

test/go.mod

@@ -7,7 +7,7 @@ toolchain go1.24.1
 require (
 	github.com/Azure/terraform-module-test-helper v0.32.0
 	github.com/gruntwork-io/terratest v0.48.2
-	github.com/hashicorp/go-retryablehttp v0.7.7
+	github.com/hashicorp/go-retryablehttp v0.7.8
 	github.com/stretchr/testify v1.10.0
 )