Merge pull request rust-postgres#527 from sfackler/dependabot/cargo/md5-0.7

Update md5 requirement from 0.6 to 0.7

Author: sfackler

postgres-protocol/Cargo.toml

@@ -15,7 +15,7 @@ bytes = "0.5"
 fallible-iterator = "0.2"
 generic-array = "0.13"
 hmac = "0.7"
-md5 = "0.6"
+md5 = "0.7"
 memchr = "2.0"
 rand = "0.7"
 sha2 = "0.8"