tailcfg: bump CurrentCapabilityVersion to capture SSH agent forwarding fix

Updates #12467

Signed-off-by: Percy Wegmann <[email protected]>

tailcfg/tailcfg.go

@@ -141,7 +141,8 @@ type CapabilityVersion int
 //   - 98: 2024-06-13: iOS/tvOS clients may provide serial number as part of posture information
 //   - 99: 2024-06-14: Client understands NodeAttrDisableLocalDNSOverrideViaNRPT
 //   - 100: 2024-06-18: Client supports filtertype.Match.SrcCaps (issue #12542)
-const CurrentCapabilityVersion CapabilityVersion = 100
+//   - 101: 2024-07-01: Client supports SSH agent forwarding when handling connections with /bin/su
+const CurrentCapabilityVersion CapabilityVersion = 101
 
 type StableID string