fix ci yapf command if no python files found

.drone.jsonnet

@@ -21,7 +21,7 @@ local PipelineLinting = {
       },
       commands: [
         'pip install -qq yapf',
-        'yapf -dr ./',
+        '[ ! -z "$(find .  -type f -name *.py)" ] && yapf -rd ./',
       ],
     },
     {

.drone.yml

@@ -16,7 +16,7 @@ steps:
   image: python:3.9
   commands:
   - pip install -qq yapf
-  - yapf -dr ./
+  - "[ ! -z \"$(find .  -type f -name *.py)\" ] && yapf -rd ./"
   environment:
     PY_COLORS: 1
 
@@ -147,6 +147,6 @@ depends_on:
 
 ---
 kind: signature
-hmac: f68c420ba798e42d0d8139489077f09936aa778877de5f0ca7690629fd79e45f
+hmac: b9d804778d467d03534c37b87dc2830ce1b7830d1f6d2a972bf8b81b038c8178
 
 ...