Update code for Crystal 0.36.0

Rename `HTTPClient@socket` to `HTTPClient@io`, see
https://github.com/crystal-lang/crystal/pull/9543.

Rename `URI#full_path` to `URI#request_target`, see
https://github.com/crystal-lang/crystal/pull/10099.

src/invidious/helpers/proxy.cr

@@ -71,14 +71,14 @@ end
 class HTTPClient < HTTP::Client
   def set_proxy(proxy : HTTPProxy)
     begin
-      @socket = proxy.open(host: @host, port: @port, tls: @tls, connection_options: proxy_connection_options)
+      @io = proxy.open(host: @host, port: @port, tls: @tls, connection_options: proxy_connection_options)
     rescue IO::Error
-      @socket = nil
+      @io = nil
     end
   end
 
   def unset_proxy
-    @socket = nil
+    @io = nil
   end
 
   def proxy_connection_options

src/invidious/helpers/utils.cr

@@ -329,7 +329,7 @@ def get_referer(env, fallback = "/", unroll = true)
     end
   end
 
-  referer = referer.full_path
+  referer = referer.request_target
   referer = "/" + referer.gsub(/[^\/?@&%=\-_.0-9a-zA-Z]/, "").lstrip("/\\")
 
   if referer == env.request.path