Not enable the rustls feature by default for sqlx

DB's like sqlite not need the tls feature with sqlx at all.
When cross compiling e.g. to i586, ring is not supported and
therefore the db-pool cannot be used because the rustls
feature is turned on by default even though not needed.

contrib/db_pools/lib/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rocket_db_pools"
-version = "0.1.0"
+version = "0.2.1"
 authors = ["Sergio Benitez <sb@sergio.bz>", "Jeb Rosen <jeb@jebrosen.com>"]
 description = "Rocket async database pooling support"
 repository = "https://github.com/rwf2/Rocket/tree/master/contrib/db_pools"
@@ -26,8 +26,18 @@ sqlx_postgres = ["sqlx", "sqlx/postgres", "log"]
 sqlx_sqlite = ["sqlx", "sqlx/sqlite", "log"]
 sqlx_macros = ["sqlx/macros"]
 # diesel features
-diesel_postgres = ["diesel-async/postgres", "diesel-async/deadpool", "deadpool", "diesel"]
-diesel_mysql = ["diesel-async/mysql", "diesel-async/deadpool", "deadpool", "diesel"]
+diesel_postgres = [
+    "diesel-async/postgres",
+    "diesel-async/deadpool",
+    "deadpool",
+    "diesel",
+]
+diesel_mysql = [
+    "diesel-async/mysql",
+    "diesel-async/deadpool",
+    "deadpool",
+    "diesel",
+]
 # implicit features: mongodb
 
 [dependencies.rocket]
@@ -77,7 +87,7 @@ optional = true
 [dependencies.sqlx]
 version = "0.8"
 default-features = false
-features = ["runtime-tokio-rustls"]
+features = ["runtime-tokio"]
 optional = true
 
 [dependencies.log]