Don't drop the serde_json dependency from the json feature

reqwest-fix-metadata-auto.diff

@@ -1,14 +1,5 @@
 --- reqwest-0.11.12/Cargo.toml	1970-01-01T00:00:01+00:00
 +++ reqwest-0.11.12/Cargo.toml	1970-01-01T00:00:01+00:00
-@@ -179,7 +179,7 @@
-     "async-compression/gzip",
-     "tokio-util",
- ]
--json = ["serde_json"]
-+json = []
- multipart = ["mime_guess"]
- native-tls = ["default-tls"]
- native-tls-alpn = [
 @@ -374,41 +374,3 @@
  ]
  default-features = false