Don't install fog-aws and mime-types gems in scripts/prepare_build.sh

Instead, install them only for the 'update-knapsack' job.
Signed-off-by: Rémy Coutable <remy@rymai.me>

.gitlab-ci.yml

@@ -180,6 +180,7 @@ update-knapsack:
   <<: *only-canonical-masters
   stage: post-test
   script:
+    - retry gem install fog-aws mime-types
     - scripts/merge-reports ${KNAPSACK_RSPEC_SUITE_REPORT_PATH} knapsack/${CI_PROJECT_NAME}/rspec-pg_node_*.json
     - scripts/merge-reports ${KNAPSACK_SPINACH_SUITE_REPORT_PATH} knapsack/${CI_PROJECT_NAME}/spinach-pg_node_*.json
     - '[[ -z ${KNAPSACK_S3_BUCKET} ]] || scripts/sync-reports put $KNAPSACK_S3_BUCKET $KNAPSACK_RSPEC_SUITE_REPORT_PATH $KNAPSACK_SPINACH_SUITE_REPORT_PATH'

scripts/prepare_build.sh

@@ -10,7 +10,7 @@ fi
 
 # Only install knapsack after bundle install! Otherwise oddly some native
 # gems could not be found under some circumstance. No idea why, hours wasted.
-retry gem install knapsack fog-aws mime-types
+retry gem install knapsack
 
 cp config/gitlab.yml.example config/gitlab.yml