Add rainemak to multimedia developers

maintainers.yaml

@@ -456,7 +456,7 @@
     annotation: "GStreamer and associated packages. Codec libraries should appear in here if they are detected and used during the configure phase of a build of Gstreamer or one of its plugins. Note that package here may overlap with pulseaudio's domain, so changes should be verified with that too."
     roles:
       - maintainer: [abranson]
-      - developer: [pvuorela, r0kk3rz, tomin, kende, MikeSalmela, mal]
+      - developer: [pvuorela, r0kk3rz, tomin, kende, MikeSalmela, mal, rainemak]
 - package-group:
     team: Multimedia
     packages: