chore(deps): update golang version sync

Author: renovate[bot]

Dockerfile

@@ -1,7 +1,7 @@
 # Build the krop-controller binary (the single kcp controller at ./cmd/controller).
 # Multi-arch: the builder runs on $BUILDPLATFORM and cross-compiles Go to $TARGETARCH;
 # the distroless runtime stage has no RUN, so amd64+arm64 needs no QEMU.
-FROM --platform=$BUILDPLATFORM golang:1.26 AS build
+FROM --platform=$BUILDPLATFORM golang:1.26@sha256:3aff6657219a4d9c14e27fb1d8976c49c29fddb70ba835014f477e1c70636647 AS build
 ARG TARGETOS
 ARG TARGETARCH
 ARG VERSION=dev

flake.nix

@@ -24,7 +24,7 @@
       {
         devShells.default = dev-kit.lib.mkShell {
           inherit system;
-          goVersion = "1.26.4";
+          goVersion = "1.26.5";
           # Private module host: skip the public proxy/sumdb for our GitLab modules.
           env.GOPRIVATE = "gitlab.opendefense.cloud";
         };

go.mod

@@ -1,6 +1,6 @@
 module go.opendefense.cloud/krop-controller
 
-go 1.26.4
+go 1.26.5
 
 require (
 	github.com/kcp-dev/logicalcluster/v3 v3.0.5