Revert "added the openssl-sys to the cargo.toml"

This reverts commit 50b25765

Cargo.toml

@@ -14,10 +14,3 @@ lettre = { version = "0.10.0-rc.4", features = [
   "smtp-transport",
   "native-tls",
 ] }
-openssl-sys = "*"
-
-[features]
-# Force openssl-sys to staticly link in the openssl library. Necessary when
-# cross compiling to x86_64-unknown-linux-musl and 32 bit.
-vendored = ["openssl-sys/vendored"]
-