all: build with Go 1.26.8

Docker images take 1.26.9; nixpkgs 26.05 ships 1.26.8.
Go 1.27 needs the newer tailscale.com that main carries.

flake.lock

@@ -1,27 +1,5 @@
 {
   "nodes": {
-    "flake-checks": {
-      "inputs": {
-        "flake-utils": "flake-utils",
-        "nixpkgs": [
-          "nixpkgs"
-        ],
-        "treefmt-nix": "treefmt-nix"
-      },
-      "locked": {
-        "lastModified": 1783015821,
-        "narHash": "sha256-vmzYTZxIAy3OYXwkRL5GQYk8fNnh8TLWcxQRIO3ywOU=",
-        "owner": "kradalby",
-        "repo": "flake-checks",
-        "rev": "3c821706eb0bd07f515f9a7726b650ccae927433",
-        "type": "github"
-      },
-      "original": {
-        "owner": "kradalby",
-        "repo": "flake-checks",
-        "type": "github"
-      }
-    },
     "flake-utils": {
       "inputs": {
         "systems": "systems"
@@ -42,16 +20,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1784421286,
-        "narHash": "sha256-YKn3t7FvaargtyNHbrOw+qzDM+93q5kSCREUPNxeZQs=",
+        "lastModified": 1791765022,
+        "narHash": "sha256-ZGq3ptZzA+oO0N/Wi/F+GbuTijLkYExD01LvpNFAvr0=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "62eaae30cd05c04718500ddb44e7ef85cd45ddd5",
+        "rev": "7993f34ee47e28a3d607a525aadc6c94b73be728",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "staging-next-26.05",
+        "ref": "nixos-26.05",
         "repo": "nixpkgs",
         "type": "github"
       }