version.py: fix support for Python < 3.9

diff --git a/version.py b/version.py
index 85f3b71..5617cae 100755 (executable)
--- a/version.py
+++ b/version.py
@@ -20,5 +20,5 @@ cmd = [
 ]
 
 result = subp.run(cmd, stdout=subp.PIPE, encoding="utf-8", check=True)
-version = result.stdout.strip().removeprefix("release-")
+version = result.stdout.strip().replace("release-", "", 1)
 print(version)