workflows/pypi: fix error.

You have an error in your yaml syntax on line 6.

Signed-off-by: Steve Jeong <how2soft@gmail.com>
diff --git a/.github/workflows/pypi.yaml b/.github/workflows/pypi.yaml
index eec0e62..c5f7055 100644
--- a/.github/workflows/pypi.yaml
+++ b/.github/workflows/pypi.yaml
@@ -1,6 +1,6 @@
 name: 'PyPI upload'
 
-#on:
+on:
 #  push:
 #    paths:
 #      - 'setup.py'