go.toolchain.{rev,next.rev}: update to Go 1.25.7 / Go 1.26rc3 (#18633)

Updates #18629

Signed-off-by: Andrew Lytvynov <awly@tailscale.com>

go.mod

@@ -1,6 +1,6 @@
 module tailscale.com
 
-go 1.25.6
+go 1.25.7
 
 require (
 	filippo.io/mkcert v1.4.4

go.toolchain.next.rev

@@ -1 +1 @@
-64a6cb4cba579e2865654747d4d672ead07b8375
+5ba287c89a4cef2f4a419aed4e6bc3121c5c4dad

go.toolchain.rev

@@ -1 +1 @@
-779d878b6a943cecd2f359699001a03d7cedf222
+692441891e061f8ae2cb2f8f2c898f86bb1c5dca

go.toolchain.rev.sri

@@ -1 +1 @@
-sha256-e081DbI45vGMmi3drwqz2UOxRwffEuEDSVZupDtOVuk=
+sha256-gWKrpBTXfsQmgOWoMrbvCaWGsBXCt5X12BAcwfAPMQY=

go.toolchain.version

@@ -1 +1 @@
-1.25.6
+1.25.7

pull-toolchain.sh

@@ -25,6 +25,7 @@ fi
 # don't yet support TS_GO_NEXT=1 with flake.nix or in our corp CI.
 if [ "${TS_GO_NEXT:-}" != "1" ]; then
     ./tool/go version 2>/dev/null | awk '{print $3}' | sed 's/^go//' > go.toolchain.version
+    ./tool/go mod edit -go "$(cat go.toolchain.version)"
     ./update-flake.sh
 fi