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
 
@@ -115,6 +115,6 @@ depends_on:
 
 ---
 kind: signature
-hmac: 541fc5ad55308be09fa538bdc954154b699d6e65799f4aa4543d1d36ff115b56
+hmac: f28d20ad65f77a993336afc9d3a58f554bf46511e9b4cb1e5ffdd0b49041e02d
 
 ...