Handle inferring electron-prebuilt-compile versions better

[malept]

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• The changes are appropriately documented (if applicable).
• The changes have sufficient test coverage (if applicable).
• The testsuite passes successfully on my local machine (if applicable).

Summarize your changes:

In electron-prebuilt-compile 1.6.5, a main file was added, so we can use the normal way of inferring the version instead of using the workaround.

Fixes #909.

CC: @jacobq

[codecov]

Codecov Report

Merging #932 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #932   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          12     12           
  Lines         669    672    +3     
=====================================
+ Hits          669    672    +3

Impacted Files	Coverage Δ
infer.js	100% <100%> (ø)	⬆️

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