Redirect youtu.be links to the correct instance

Farside was previously only looking for links containing "youtube.com"
when performing the redirect for full URLs to youtube, which obviously
doesn't work for youtu.be shortened links. This updates the matching
logic to use a regex element for every key in the services map in order
to match against multiple possible domains for each parent service.

Fixes #40

lib/farside.ex

@@ -7,15 +7,15 @@ defmodule Farside do
   # This enables Farside to redirect with links such as:
   # farside.link/https://www.youtube.com/watch?v=dQw4w9WgXcQ
   @parent_services %{
-    "youtube.com" => ["invidious", "piped"],
-    "reddit.com" => ["libreddit", "teddit"],
-    "instagram.com" => ["bibliogram"],
-    "twitter.com" => ["nitter"],
-    "wikipedia.org" => ["wikiless"],
-    "medium.com" => ["scribe"],
-    "odysee.com" => ["librarian"],
-    "imgur.com" => ["rimgo"],
-    "translate.google.com" => ["lingva"]
+    ~r/youtu(.be|be.com)/ => ["invidious", "piped"],
+    ~r/reddit.com/ => ["libreddit", "teddit"],
+    ~r/instagram.com/ => ["bibliogram"],
+    ~r/twitter.com/ => ["nitter"],
+    ~r/wikipedia.org/ => ["wikiless"],
+    ~r/medium.com/ => ["scribe"],
+    ~r/odysee.com/ => ["librarian"],
+    ~r/imgur.com/ => ["rimgo"],
+    ~r/translate.google.com/ => ["lingva"]
   }
 
   def get_services_map do
@@ -49,7 +49,7 @@ defmodule Farside do
         Enum.find_value(
           @parent_services,
           fn {k, v} ->
-            service =~ k && Enum.random(v)
+            String.match?(service, k) && Enum.random(v)
           end)
       true ->
         service