Update prometheus to v0.11.x (#435)

Author: jtescher

opentelemetry-prometheus/Cargo.toml

@@ -21,10 +21,10 @@ rustdoc-args = ["--cfg", "docsrs"]
 
 [dependencies]
 opentelemetry = { version = "0.11", path = "../opentelemetry", default-features = false, features = ["metrics"] }
-prometheus = "0.10"
+prometheus = "0.11"
 protobuf = "2.14"
 
 [dev-dependencies]
 tokio = { version = "1.0", features = ["full"] }
-hyper = "0.14"
+hyper = { version = "0.14", features = ["full"] }
 lazy_static = "1.4"