Add missing OpenSSL depend

[henningkayser]

Should fix #59

[codecov]

Codecov Report

Merging #62 (e956e7a) into ros2 (8f15296) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             ros2      #62   +/-   ##
=======================================
  Coverage   72.73%   72.73%           
=======================================
  Files           5        5           
  Lines         242      242           
=======================================
  Hits          176      176           
  Misses         66       66           

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