v2.2.0

New Rules

• DL3060: Lint for yarn cache clean #395 (#592)
• DL3059: Multiple consecutive RUN instructions (#591)

Bugfixes

• json-formatter: fix error message (#594)
• DL3005: allow apt-get upgrade (fix #562) (#596)
• DL3059: improve behaviour when considering flags (#595)
• Fixed #444 ("missing whitespace" error when using the 'required' option for a secret mount in RUN)
• Improved error message for the configuration file (#600)
• DL3042: respect PIP_NO_CACHE_DIR variable (#604)