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: 628d21813aa5ac53cd88da2f20e49b81ddab8ce1b3e861cb82ae2b44396ac612
+hmac: a4be6f26e3731b8f9e3b5daccc58b918320bed363a584a5d7c33475bbdf07e2a
 
 ...