chore!: drop support for Node 12; finish adding support for Node 18

[nolanmar511]

Breaking change

Blocked by mapbox/node-pre-gyp#647

[codecov-commenter]

Codecov Report

Merging #215 (78d387b) into main (f6ac01d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #215   +/-   ##
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  Coverage   42.21%   42.21%           
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  Files          14       14           
  Lines        2061     2061           
  Branches       42       42           
=======================================
  Hits          870      870           
  Misses       1173     1173           
  Partials       18       18           

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[rauno56]

Depending on your build setup, this should now be straight-forward to enable. nan has to definitely be upgraded.
We're using prebuildify instead of node-pre-gyp though. See signalfx/splunk-otel-js@25a24ac

[nolanmar511]

Based on the success of the ci/kokoro: system test with Node 18, it's likely that if one installs from code on Github and looks at node-gyp to ensure one has dependencies necessary to build binaries (documentation notes these) one will be able to use the pprof-nodejs repo with Node 18. pprof-nodejs (at head) is already tested against the v8-canary regularly.

I don't think that I would recommend this for production code; but for experimentation with Node 18, this approach may work.

As noted in the CL description, this CL's submission is currently blocked by a node-pre-gyp issue (which prevents pre-built binaries from being created given out current release process).

[nolanmar511]

Closing this PR based on mapbox/node-pre-gyp#657.

Given the current state of node-pre-gyp and my current level of involvement with this repo, I do not think I'm the right owner for adding Node 18 support.