bump compat for Cairo.jl to 1.0

[Mattriks]

• I've run the regression tests
• I've built the docs and confirmed these changes don't cause new errors
• I ran test Gadfly on Julia 1.3 with this branch, and there were no errors

This PR:

• closes compats #374

[codecov-io]

Codecov Report

Merging #376 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #376   +/-   ##
=======================================
  Coverage   40.81%   40.81%           
=======================================
  Files          18       18           
  Lines        3058     3058           
=======================================
  Hits         1248     1248           
  Misses       1810     1810

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