ci: switch to drone-matrix plugin

.drone.yml

@@ -166,7 +166,7 @@ steps:
         - success
 
   - name: matrix
-  image: plugins/matrix
+    image: thegeeklab/drone-matrix
     settings:
       homeserver:
         from_secret: matrix_homeserver
@@ -174,7 +174,7 @@ steps:
         from_secret: matrix_password
       roomid:
         from_secret: matrix_roomid
-    template: "Status: **{{ build.status }}**<br/> Build: [{{ repo.Owner }}/{{ repo.Name }}]({{ build.link }}) ({{ build.branch }}) by {{ build.author }}<br/> Message: {{ build.message }}"
+      template: "Status: **{{ build.Status }}**<br/> Build: [{{ repo.Owner }}/{{ repo.Name }}]({{ build.Link }}) ({{ build.Branch }}) by {{ commit.Author }}<br/> Message: {{ commit.Message }}"
       username:
         from_secret: matrix_username
     when:
@@ -195,6 +195,6 @@ depends_on:
 
 ---
 kind: signature
-hmac: a1f7400028453cb7a43a23cc25eaae9e6b1eb972eb83153b6d37dc09b8b6d00b
+hmac: 42102b6f3eaabc013a3cd1f354c043462e9654f26f46a2e239f5af92d6109e85
 
 ...