chore(deps): update golang docker tag to v1.26 (#760)

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

Author: renovate[bot]

docs/demo/docker-compose.yaml

@@ -123,7 +123,7 @@ services:
       #language=dockerfile
       dockerfile_inline: |
         # renovate: docker=golang
-        FROM golang:1.25-alpine
+        FROM golang:1.26-alpine
 
         RUN go install github.com/jkroepke/openvpn-auth-oauth2@latest
     restart: unless-stopped