Bump gopkg.in/yaml.v3 in /functions/async/pubsub/producer

Bumps gopkg.in/yaml.v3 from 3.0.0-20210107192922-496545a6307b to 3.0.0.

---
updated-dependencies:
- dependency-name: gopkg.in/yaml.v3
  dependency-type: indirect
...

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

Author: dependabot[bot]

functions/async/pubsub/producer/go.mod

@@ -17,5 +17,5 @@ require (
 	google.golang.org/genproto v0.0.0-20210831024726-fe130286e0e2 // indirect
 	google.golang.org/grpc v1.40.0 // indirect
 	google.golang.org/protobuf v1.27.1 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	gopkg.in/yaml.v3 v3.0.0 // indirect
 )