Update repository_rules.bzl

[cgrinker]

Adding starlark string coercion to fix error: unsupported operand type(s) for +: 'string' and 'int'

Discussion

This error hides the real error code when trying to read in the attributes file

I proced this error building the //google/api:annotations_proto rule in the googleapis/googleapis repository. The api_annotations and swagger gen rules are used int the googleforgames/open-match project, whose protocol buffer rules I'm trying to run.

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[cgrinker]

I signed it!

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[codecov]

Codecov Report

Merging #730 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #730   +/-   ##
=========================================
  Coverage     77.43%   77.43%           
  Complexity     1081     1081           
=========================================
  Files           196      196           
  Lines          4707     4707           
  Branches        369      369           
=========================================
  Hits           3645     3645           
  Misses          895      895           
  Partials        167      167

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[vam-google]

LGTM

[vam-google]

@cgrinker Thanks a lot for fixing this! I believe nobody has ever seen this pull request (it does not have a corresponding issue and was not assigned to anyone), that is why it was ignored.

Merging in