Revert "ci pycall: increase timeout"

This reverts commit 303adeb.

The current timeout is enough. It seems that tests got stuck.

Author: kou

.github/workflows/pycall.yml

@@ -16,7 +16,7 @@ jobs:
     needs: ruby-versions
     name: ${{ matrix.os }}/${{ matrix.ruby }}/${{ matrix.python }}-${{ matrix.python_architecture }}
     runs-on: ${{ matrix.os }}
-    timeout-minutes: 15
+    timeout-minutes: 10
 
     strategy:
       fail-fast: false