Macro recursion decrease and other optimizations

- Decreased `recursion_limit` from 512 to 87
  Mainly done by optimizing the config macro's.
  This fixes an issue with the rust-analyzer which doesn't go beyond 128
- Removed Regex for masking sensitive values and replaced it with a map()
  This is much faster then using a Regex.
- Refactored the get_support_json macro's
- All items above also lowered the binary size and possibly compile-time
- Removed `_conn: DbConn` from several functions, these caused unnecessary database connections for functions who didn't used that at all
- Decreased json response for `/plans`
- Updated libraries and where needed some code changes
  This also fixes some rare issues with SMTP https://github.com/lettre/lettre/issues/678
- Using Rust 2021 instead of 2018
- Updated rust nightly

src/api/notifications.rs

@@ -4,7 +4,7 @@ use rocket::Route;
 use rocket_contrib::json::Json;
 use serde_json::Value as JsonValue;
 
-use crate::{api::EmptyResult, auth::Headers, db::DbConn, Error, CONFIG};
+use crate::{api::EmptyResult, auth::Headers, Error, CONFIG};
 
 pub fn routes() -> Vec<Route> {
     routes![negotiate, websockets_err]
@@ -30,7 +30,7 @@ fn websockets_err() -> EmptyResult {
 }
 
 #[post("/hub/negotiate")]
-fn negotiate(_headers: Headers, _conn: DbConn) -> Json<JsonValue> {
+fn negotiate(_headers: Headers) -> Json<JsonValue> {
     use crate::crypto;
     use data_encoding::BASE64URL;