fix(webapp): pin goose builder to go 1.26.10

Mono-RevId: acde560ac6ade661e28982a0a921dea6abe7ee76
(cherry picked from commit 39483a7)

Author: nicktrn

docker/Dockerfile

@@ -6,7 +6,7 @@ ARG NODE_IMAGE=node:24.22.1-bookworm-slim@sha256:55fb5f5a527ea2c5c4a95f963e48ef9
 # local `docker build` or compose build leaves it unset and caches as usual.
 ARG APT_REFRESH=unset
 
-FROM golang:1.26-alpine AS goose_builder
+FROM golang:1.26.10-alpine@sha256:9ce231b28998b32e116927c61aa5c406183061d4f3f2d61b292c88e7f6bdf7ca AS goose_builder
 RUN go install github.com/pressly/goose/v3/cmd/goose@v3.27.1
 
 FROM ${NODE_IMAGE} AS pruner