Simplify Dockerfile further

Dockerfile

@@ -7,12 +7,10 @@ COPY ./docker/clone-and-preflight.js ./docker/package.json ./docker/pnpm-lock.ya
 RUN corepack enable && corepack prepare pnpm@latest --activate
 RUN pnpm install --frozen-lockfile
 
-# Enable `pnpm add --global` on Alpine Linux
-# - Set the home location environment variable to a location already in $PATH
-# - Trick pnpm into thinking that bash is available (only /bin/sh available on Alpine Linux)
+# Enable `pnpm add --global` on Alpine Linux by setting
+# home location environment variable to a location already in $PATH
 # https://github.com/pnpm/pnpm/issues/784#issuecomment-1518582235
 ENV PNPM_HOME=/usr/local/bin
-RUN SHELL=bash pnpm setup
 
 RUN pnpm add --global @upleveled/preflight