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: fbe5213306c3dd4c4aca4fe6bce6e21c7ed281cb9c4a4dfade0cbb44cc03f18c
+hmac: 3f875c4bbfd7065bba4c041d41e4355e3412bccc4bc0f00afea627ad91d53115
 
 ...