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
 
@@ -180,6 +180,6 @@ depends_on:
 
 ---
 kind: signature
-hmac: 1d657bf14cd9040e9c1d02419f225f885391cef39b82e72d18f7a240b6222a0b
+hmac: d93f283cfefa16c01d8fd7fe9f19d1d0183806f394d3bb85ca95bb737d87e792
 
 ...