Added optional rustls feature (#27)

With this commit you can choose to use rustls instead of native-tls

Co-authored-by: Bryley Hayter <[email protected]>

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name        = "gql_client"
-version     = "1.0.7"
+version     = "1.0.8"
 authors     = ["Arthur Khlghatyan <[email protected]>"]
 edition     = "2018"
 description = "Minimal GraphQL client for Rust"
@@ -14,11 +14,17 @@ categories  = ["web-programming", "asynchronous"]
 [badges]
 maintenance = { status = "actively-developed" }
 
+[features]
+default = ["native-tls"]
+
+native-tls = ["reqwest/native-tls"]
+rustls-tls = ["reqwest/rustls-tls"]
+
 [dependencies]
 serde      = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
-reqwest    = { version = "0.11", features = ["json"] }
+reqwest    = { version = "0.11", features = ["json"], default_features = false }
 log        = "0.4"
 
 [dev-dependencies]
-tokio = { version = "1", features = ["full"] }
+tokio = { version = "1", features = ["full"] }