ci: switch to drone-matrix plugin

.drone.yml

@@ -172,7 +172,7 @@ steps:
         - success
 
   - name: matrix
-  image: plugins/matrix
+    image: thegeeklab/drone-matrix
     settings:
       homeserver:
         from_secret: matrix_homeserver
@@ -180,7 +180,7 @@ 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:
@@ -201,6 +201,6 @@ depends_on:
 
 ---
 kind: signature
-hmac: dc637988ad9e93c35aee6647a831e613f118821b75a99b76655ca0e18661fa08
+hmac: 44c52e98f1e69ded6f76d25a7f95b64750190de295efa1bfadd24bdfe8ecf15c
 
 ...