replace lru-cache dependency

[wraithgar]

This is a rebase of https://github.com/npm/node-semver/pull/697 to isolate the changes into two discrete commits.

• deps: remove lru-cache
• fix: use internal cache implementation

[wraithgar]

Our linting rules have updated, I'll add a third linting commit to this PR

[wraithgar]

Test failures are due to removal of test runners. We still test in those node versions in other parts of the testing matrix.

[mbtools]

nice 👍