chore: add eslint fixes

fix: bump package version for release

Extra commit as the previous two were tagged as `chore` not `fix` and hence the standard release didn't trigger any release at all.

test(events): demensions and metrics packaged in payload

fix: trim correctly catches integer values

On giving any non-string value to any of the parameters of ReactGA.event we are getting error r.replace is not a function,  add s.toString().replace so we will get no error.

fix(timing): skip warning for falsy value

feat: allow onerror callback in loadGA

This will allow callers to set an onerror callback on the script tag for Google Analytics. Some ad blockers cause Google Analytics to fail to load so this would allow callers to handle that error.

ci: fix version command

Merge pull request react-ga#387 from SimeonC/master

Merge in version.

Merge pull request react-ga#357 from SimeonC/master

Version 2.6.0 PR

2.6.0