Bump github.com/stretchr/testify from 1.8.4 to 1.9.0 (closes #20)

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.8.4 to 1.9.0.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](https://github.com/stretchr/testify/compare/v1.8.4...v1.9.0)

Change-Id: I1024f4fd30d3be35306cf54e1006d30552ad5665

---
updated-dependencies:
- dependency-name: github.com/stretchr/testify
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Change-Id: I849aee7b5e526c0d405bca0fcc9b0decf48c6987
diff --git a/go.mod b/go.mod
index 4b010aa..95d6935 100644
--- a/go.mod
+++ b/go.mod
@@ -12,7 +12,7 @@
 	github.com/gin-gonic/gin v1.9.1
 	github.com/joho/godotenv v1.5.1
 	github.com/mattn/go-jsonpointer v0.0.1
-	github.com/stretchr/testify v1.8.4
+	github.com/stretchr/testify v1.9.0
 	golang.org/x/text v0.14.0
 )