chore(deps): update python docker tag to v3.12

docker/Dockerfile

@@ -10,7 +10,7 @@ RUN go build -ldflags='-s -w -extldflags "-static"' -o /bin/mym ./cmd/mym
 FROM node:18-alpine AS node-builder
 RUN npm i --silent -g vercel
 
-FROM python:3.9-alpine
+FROM python:3.12-alpine
 RUN apk update && apk add --no-cache gcc musl-dev libffi-dev
 RUN pip install datasette
 RUN datasette install datasette-publish-vercel