feat(release-backed): allow a candidate release to be published to next tag

[bcoe]

Give release backed publications the ability to publish to a next tag on npm.

[codecov]

Codecov Report

Merging #66 into master will increase coverage by 0.31%.
The diff coverage is 43.07%.

@@            Coverage Diff             @@
##           master      #66      +/-   ##
==========================================
+ Coverage   28.72%   29.03%   +0.31%     
==========================================
  Files          18       18              
  Lines        2214     2228      +14     
  Branches       84       92       +8     
==========================================
+ Hits          636      647      +11     
- Misses       1578     1581       +3     

Impacted Files	Coverage Δ
.prettierrc.js	0.00% <0.00%> (ø)
src/lib/unsafe.ts	0.00% <0.00%> (ø)
src/server.ts	0.00% <0.00%> (ø)
src/lib/json.ts	91.30% <33.33%> (ø)
src/lib/write-package.ts	73.28% <73.91%> (+0.06%)	⬆️
src/lib/github.ts	62.00% <87.50%> (+0.51%)	⬆️
src/lib/datastore.ts	30.85% <100.00%> (ø)
src/lib/packument.ts	46.45% <100.00%> (ø)
... and 3 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update def54fb...7a21c82. Read the comment docs.