Changes in version 0.2.0                        

  - Add detection of the 'air' executable (R formatter).
  - Add detection of the 'Pandoc' executable.
  - Make version parsing robust: an executable emitting an unexpected
    --version output (e.g. the Firefox snap wrapper on Ubuntu) no longer
    raises "invalid version specification" but is reported as not found.
  - Fix min_version_available(version=...)
  - Set NODE_DISABLE_COMPILE_CACHE=1 when calling node/npm to avoid
    leaving a node-compile-cache directory in the temp directory.

                 Changes in version 0.1.1 (2021-05-19)                  

  - Added some timeout when system2 is called.
  - change python reference order for execs, see .exec_names$python and
    .exec_names$pip