go.toolchain{,.next}.rev: bump Go 1.27 to pick up mips64 stkobj alignment fix

The previous tailscale.go1.27 build (based on go1.27rc2) crashed all
linux/mips64 and mips64le binaries with SIGBUS under qemu-user, which
made tstest/archtest fail in CI: the compiler under-aligned the
.stkobj funcdata records that the runtime reads as uintptrs
(golang/go#80668). The new build carries the fix. Verified locally
that tstest/archtest passes for mips64 and mips64le under qemu.

Updates #20220

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: Ic0dcb8bedd988a6679191c3c8339f9377c24909f

flakehashes.json

@@ -1,7 +1,7 @@
 {
   "toolchain": {
-    "rev": "d6f02654cf98ded9688bc6863c176bacc734352d",
-    "sri": "sha256-Cf2RkgmH2A2GFJ4sgZYKXcunl1uDUEwkNK5U9rMW6Ik="
+    "rev": "73cfd991bb90b04abf6c1d6c293f091836c1048d",
+    "sri": "sha256-IsPPTtL7c4QrIdnp7zhpdhaH+IQ9lt1l3fjp52svZyM="
   },
   "vendor": {
     "goModSum": "sha256-nT82NXB/Ro2B98T2oMY++zJ6akec7Gh26bo2quiCsrs=",

go.toolchain.next.rev

@@ -1 +1 @@
-d6f02654cf98ded9688bc6863c176bacc734352d
+73cfd991bb90b04abf6c1d6c293f091836c1048d

go.toolchain.rev

@@ -1 +1 @@
-d6f02654cf98ded9688bc6863c176bacc734352d
+73cfd991bb90b04abf6c1d6c293f091836c1048d