Use rss crate for RSS feed parsing (#709)

* Refactor annoying type difference

* Add rss

* Add support for parsing RSS feeds

* Add rss lib

* Add Cargo project

* Lint rust

* changelog

* Add support for new fields

Author: Half-Shot

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "rust-analyzer.linkedProjects": [
+        "./Cargo.toml"
+    ]
+}