feat: uglify mjs by default

[alexander-akait]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

Support mjs by default

fixes #33

Breaking Changes

No

Additional Info

No

[codecov]

Codecov Report

Merging #39 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #39   +/-   ##
=======================================
  Coverage   98.47%   98.47%           
=======================================
  Files           5        5           
  Lines         262      262           
  Branches      101      101           
=======================================
  Hits          258      258           
  Misses          4        4

Impacted Files	Coverage Δ
src/index.js	97.84% <100%> (ø)	⬆️

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #39 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #39   +/-   ##
=======================================
  Coverage   98.47%   98.47%           
=======================================
  Files           5        5           
  Lines         262      262           
  Branches      101      101           
=======================================
  Hits          258      258           
  Misses          4        4

Impacted Files	Coverage Δ
src/index.js	97.84% <100%> (ø)	⬆️

---

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 e835b19...8a2c792. Read the comment docs.

[codecov]

Codecov Report

Merging #39 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master      #39   +/-   ##
=======================================
  Coverage   98.47%   98.47%           
=======================================
  Files           5        5           
  Lines         262      262           
  Branches      101      101           
=======================================
  Hits          258      258           
  Misses          4        4

Impacted Files	Coverage Δ
src/index.js	97.84% <100%> (ø)	⬆️

---

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 e835b19...8a2c792. Read the comment docs.