Update to Crystal 0.31.0, resolve compiler deprecation warnings, update dependencies (#764)

* shard: update to crystal 0.31.0

Additionally, no longer use the Crystal "markdown" library which has
been removed from the Crystal stdlib in version 0.31.0.
See https://github.com/crystal-lang/crystal/pull/8115.

Also fix some deprecation warnings using the following commands:

    find . \( -type d -name .git -prune \) -o -type f -exec sed -i 's/URI\.escape/URI\.encode_www_form/g' "{}" \;
    find . \( -type d -name .git -prune \) -o -type f -exec sed -i 's/URI\.unescape/URI\.decode_www_form/g' "{}" \;
    sed -i 's/while \%pull\.kind \!\= \:end_object/until \%pull\.kind\.end_object\?/g' src/invidious/helpers/patch_mapping.cr

src/invidious/helpers/handlers.cr

@@ -95,8 +95,8 @@ class AuthHandler < Kemal::Handler
 
     begin
       if token = env.request.headers["Authorization"]?
-        token = JSON.parse(URI.unescape(token.lchop("Bearer ")))
-        session = URI.unescape(token["session"].as_s)
+        token = JSON.parse(URI.decode_www_form(token.lchop("Bearer ")))
+        session = URI.decode_www_form(token["session"].as_s)
         scopes, expire, signature = validate_request(token, session, env.request, HMAC_KEY, PG_DB, nil)
 
         if email = PG_DB.query_one?("SELECT email FROM session_ids WHERE id = $1", session, as: String)

src/invidious/helpers/patch_mapping.cr

@@ -50,7 +50,7 @@ macro patched_json_mapping(_properties_, strict = false)
     rescue exc : ::JSON::ParseException
       raise ::JSON::MappingError.new(exc.message, self.class.to_s, nil, *%location, exc)
     end
-    while %pull.kind != :end_object
+    until %pull.kind.end_object?
       %key_location = %pull.location
       key = %pull.read_object_key
       case key

src/invidious/helpers/static_file_handler.cr

@@ -119,7 +119,7 @@ module Kemal
 
       config = Kemal.config.serve_static
       original_path = context.request.path.not_nil!
-      request_path = URI.unescape(original_path)
+      request_path = URI.decode_www_form(original_path)
 
       # File path cannot contains '\0' (NUL) because all filesystem I know
       # don't accept '\0' character as file name.

src/invidious/helpers/tokens.cr

@@ -69,7 +69,7 @@ end
 def validate_request(token, session, request, key, db, locale = nil)
   case token
   when String
-    token = JSON.parse(URI.unescape(token)).as_h
+    token = JSON.parse(URI.decode_www_form(token)).as_h
   when JSON::Any
     token = token.as_h
   when Nil

src/invidious/helpers/utils.cr

@@ -246,7 +246,7 @@ def get_referer(env, fallback = "/", unroll = true)
       if referer.query
         params = HTTP::Params.parse(referer.query.not_nil!)
         if params["referer"]?
-          referer = URI.parse(URI.unescape(params["referer"]))
+          referer = URI.parse(URI.decode_www_form(params["referer"]))
         else
           break
         end