build: fix yarn version in docker image to be the same as in local en…

…v (v3.0.1)

Dockerfile

@@ -4,15 +4,20 @@ WORKDIR /bot
 
 # 1. Cache dependencies.
 FROM base AS cache
+COPY ./.yarnrc.yml ./.yarnrc.yml
+COPY ./.yarn/ ./.yarn/
 COPY ./package.json ./package.json
 COPY ./yarn.lock ./yarn.lock
-RUN yarn install --production --ignore-scripts
+RUN yarn install --immutable
+RUN npm prune --production --no-package-lock
 
 # 2. Build the code.
 FROM base AS build
+COPY ./.yarnrc.yml ./.yarnrc.yml
+COPY ./.yarn/ ./.yarn/
 COPY ./package.json ./package.json
 COPY ./yarn.lock ./yarn.lock
-RUN yarn install --ignore-scripts
+RUN yarn install --immutable
 COPY ./src ./src
 COPY ./tsconfig.json ./tsconfig.json
 COPY ./tsconfig.prod.json ./tsconfig.prod.json