Bump github.com/stretchr/testify from 1.7.5 to 1.8.0

Bumps [github.com/stretchr/testify](https://github.com/stretchr/testify) from 1.7.5 to 1.8.0.
- [Release notes](https://github.com/stretchr/testify/releases)
- [Commits](stretchr/testify@v1.7.5...v1.8.0)

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

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

go.mod

@@ -60,7 +60,7 @@ require (
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.12.0
 	github.com/spiffe/go-spiffe/v2 v2.1.0
-	github.com/stretchr/testify v1.7.5
+	github.com/stretchr/testify v1.8.0
 	github.com/theupdateframework/go-tuf v0.3.0
 	github.com/titanous/rocacheck v0.0.0-20171023193734-afe73141d399
 	github.com/transparency-dev/merkle v0.0.1

go.sum

@@ -2136,8 +2136,8 @@ github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.2/go.mod h1:R6va5+xMeoiuVRoj+gSkQ7d3FALtqAAGI1FQKckRals=
-github.com/stretchr/testify v1.7.5 h1:s5PTfem8p8EbKQOctVV53k6jCJt3UX4IEJzwh+C324Q=
-github.com/stretchr/testify v1.7.5/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/subosito/gotenv v1.2.0/go.mod h1:N0PQaV/YGNqwC0u51sEeR/aUtSLEXKX9iv69rRypqCw=
 github.com/subosito/gotenv v1.3.0 h1:mjC+YW8QpAdXibNi+vNWgzmgBH4+5l5dCXv8cNysBLI=
 github.com/subosito/gotenv v1.3.0/go.mod h1:YzJjq/33h7nrwdY+iHMhEOEEbW0ovIz0tB6t6PwAXzs=