zulip_tools: Shell out to python to get true ZULIP_VERSION.

Parsing veryion.py will not get extended version information from git.

scripts/lib/zulip_tools.py

@@ -108,10 +108,13 @@ def get_deploy_root() -> str:
 
 
 def parse_version_from(deploy_path: str) -> str:
-    with open(os.path.join(deploy_path, "version.py")) as f:
-        result = re.search('ZULIP_VERSION = "(.*)"', f.read())
-        if result:
-            return result.groups()[0]
+    try:
+        return subprocess.check_output(
+            [sys.executable, "-c", "from version import ZULIP_VERSION; print(ZULIP_VERSION)"],
+            cwd=deploy_path,
+            text=True,
+        ).strip()
+    except subprocess.CalledProcessError:
         return "0.0.0"