ci: switch to drone-matrix plugin

.drone.yml

@@ -184,7 +184,7 @@ steps:
         - success
 
   - name: matrix
-  image: plugins/matrix
+    image: thegeeklab/drone-matrix
     settings:
       homeserver:
         from_secret: matrix_homeserver
@@ -192,7 +192,7 @@ 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:
@@ -213,6 +213,6 @@ depends_on:
 
 ---
 kind: signature
-hmac: c154ec6b9e2c325bc15353640277a9e618e69cbd5e433c9439e833e2694aba4e
+hmac: e79ac30892015d4a53e0981ac2568945732414feba8f108ec4ad89a3aa3c9544
 
 ...