Revert jobs back to 1.

Author: conradwt

Dockerfile

@@ -55,14 +55,14 @@ COPY Gemfile Gemfile.lock vendor ./
 RUN bundle install && \
     rm -rf ~/.bundle/ "${BUNDLE_PATH}"/ruby/*/cache "${BUNDLE_PATH}"/ruby/*/bundler/gems/*/.git && \
     # -j 1 disable parallel compilation to avoid a QEMU bug: https://github.com/rails/bootsnap/issues/495
-    bundle exec bootsnap precompile -j 0 --gemfile
+    bundle exec bootsnap precompile -j 1 --gemfile
 
 # Copy application code
 COPY . .
 
 # Precompile bootsnap code for faster boot times.
 # -j 1 disable parallel compilation to avoid a QEMU bug: https://github.com/rails/bootsnap/issues/495
-RUN bundle exec bootsnap precompile -j 0 app/ lib/
+RUN bundle exec bootsnap precompile -j 1 app/ lib/
 
 # Precompiling assets for production without requiring secret RAILS_MASTER_KEY
 RUN SECRET_KEY_BASE_DUMMY=1 ./bin/rails assets:precompile