Bump go.opentelemetry.io/collector/model in /internal/scrapertest

Bumps [go.opentelemetry.io/collector/model](https://github.com/open-telemetry/opentelemetry-collector) from 0.47.0 to 0.50.0.
- [Release notes](https://github.com/open-telemetry/opentelemetry-collector/releases)
- [Changelog](https://github.com/open-telemetry/opentelemetry-collector/blob/main/CHANGELOG.md)
- [Commits](open-telemetry/opentelemetry-collector@v0.47.0...v0.50.0)

---
updated-dependencies:
- dependency-name: go.opentelemetry.io/collector/model
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

internal/scrapertest/go.mod

@@ -3,17 +3,25 @@ module github.com/open-telemetry/opentelemetry-collector-contrib/internal/scrape
 go 1.17
 
 require (
-	github.com/stretchr/testify v1.7.0
-	go.opentelemetry.io/collector/model v0.47.0
+	github.com/stretchr/testify v1.7.1
+	go.opentelemetry.io/collector/model v0.50.0
 	go.uber.org/multierr v1.8.0
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/kr/pretty v0.3.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	go.opentelemetry.io/collector/pdata v0.50.0 // indirect
 	go.uber.org/atomic v1.7.0 // indirect
+	golang.org/x/net v0.0.0-20201021035429-f5854403a974 // indirect
+	golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4 // indirect
+	golang.org/x/text v0.3.3 // indirect
+	google.golang.org/genproto v0.0.0-20200526211855-cb27e3aa2013 // indirect
+	google.golang.org/grpc v1.46.0 // indirect
+	google.golang.org/protobuf v1.28.0 // indirect
 	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )