Fix testpack working-directory

[wimpyprogrammer]

Fix CI errors during testpack due to sub-directory confusion.

npm WARN tarball tarball data for regex-to-strings@file:packages/regex-to-strings/regex-to-strings-2.1.0.tgz (null) seems to be corrupted. Trying again.
npm ERR! code ENOENT
npm ERR! syscall open
npm ERR! path /home/runner/work/regex-to-strings/regex-to-strings/packages/regex-to-strings-testpack/packages/regex-to-strings/regex-to-strings-2.1.0.tgz
npm ERR! errno -2
npm ERR! enoent ENOENT: no such file or directory, open '/home/runner/work/regex-to-strings/regex-to-strings/packages/regex-to-strings-testpack/packages/regex-to-strings/regex-to-strings-2.1.0.tgz'
npm ERR! enoent This is related to npm not being able to find a file.
npm ERR! enoent 

[codecov]

Codecov Report

Merging #66 (ed1daa2) into develop (1443ff1) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop      #66   +/-   ##
========================================
  Coverage    99.29%   99.29%           
========================================
  Files           22       22           
  Lines          424      424           
  Branches        69       69           
========================================
  Hits           421      421           
  Misses           2        2           
  Partials         1        1           

---

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 1443ff1...ed1daa2. Read the comment docs.