chore(deps): update golang docker tag to v1.26

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Dockerfile

@@ -12,7 +12,7 @@ RUN cargo install --path .
 FROM runtime
 COPY --from=builder /usr/local/cargo/bin/ovsinit /usr/local/bin/ovsinit
 
-FROM golang:1.21 AS ovn-kubernetes
+FROM golang:1.26@sha256:fb612b7831d53a89cbc0aaa7855b69ad7b0caf603715860cf538df854d047b84 AS ovn-kubernetes
 RUN apt-get update && \
     apt-get install --no-install-recommends -y \
         quilt