tailcfg: no-op bump of MapRequest.Version
So 1.18 and 1.20 don't have the same.
// 23: 2021-08-25: DNSConfig.Routes values may be empty (for ExtraRecords support in 1.14.1+)
// 24: 2021-09-18: MapResponse.Health from control to node; node shows in "tailscale status"
// 25: 2021-11-01: MapResponse.Debug.Exit
-const CurrentMapRequestVersion = 25
+// 26: 2022-01-12: (nothing, just bumping for 1.20.0)
+const CurrentMapRequestVersion = 26
type StableID string
