Add twirp to RPC Implementations list (#9085)

docs/third_party.md

diff --git a/docs/third_party.md b/docs/third_party.md
index ca2ac63..06b31b1 100644
--- a/docs/third_party.md
+++ b/docs/third_party.md
@@ -129,6 +129,7 @@
 * https://github.com/Yeolar/raster (C++)
 * https://github.com/jnordberg/wsrpc (JavaScript Node.js/Browser)
 * https://github.com/ppissias/xsrpcj (Java)
+* https://github.com/twitchtv/twirp (Multiple languages)
 
 Inactive: