umu_runtime: fix bug when deleting VERSIONS.txt

- The launcher would fail to restore this fail after it was deleted because it did not handle the redirect. However, even if the redirect was handled, the resource wasn't specified correctly. For now, just handle the 301 error

umu/umu_runtime.py

@@ -280,11 +280,23 @@ def _update_umu(
     # NOTE: Change 'SteamLinuxRuntime_sniper.VERSIONS.txt' when the version
     # changes (e.g., steamrt4 -> SteamLinuxRuntime_medic.VERSIONS.txt)
     if not local.joinpath("VERSIONS.txt").is_file():
-        endpoint_sniper: str = f"/{codename}/images/{build_id}"
+        versions: str = "SteamLinuxRuntime_sniper.VERSIONS.txt"
+        endpoint_sniper: str = f"/{codename}/images/{build_id}/{versions}"
         CLIENT_SESSION.request("GET", endpoint_sniper)
         resp = CLIENT_SESSION.getresponse()
         log.warning("VERSIONS.txt not found")
         log.console("Restoring VERSIONS.txt...")
+
+        # Handle the redirect
+        if resp.status == 301:
+            location: str = resp.getheader("Location")
+            log.debug("Location: %s", resp.getheader("Location"))
+            # The stdlib requires reading the entire response body before
+            # making another request
+            resp.read()
+            CLIENT_SESSION.request("GET", f"{location}/{build_id}/{versions}")
+            resp = CLIENT_SESSION.getresponse()
+
         if resp.status != 200:
             log.warning(
                 "repo.steampowered.com returned the status: %s",