adding py27 support for redirect_stdout

detect_secrets_server/adhoc/github/webhook.py

@@ -5,7 +5,18 @@
 be leaked, rather than just focusing on secrets in code.
 """
 import io
-from contextlib import redirect_stdout
+try:
+    from contextlib import redirect_stdout
+except ImportError:  # pragma: no cover
+    import sys
+    from contextlib import contextmanager
+
+    @contextmanager
+    def redirect_stdout(target):
+        original = sys.stdout
+        sys.stdout = target
+        yield
+        sys.stdout = original
 
 from detect_secrets.main import main as run_detect_secrets