proposed v3 maintenance

[msimerson]

Would you accept PRs that accomplish the following?

• replace broken Travis CI config with GitHub Actions
• bump major version to 3
• support only active Node LTS versions (automatically)
• bump package.main.engines.node to >=14
• update codecov usage to current
• update README with working badge URLs
• merge #103
• merge #93
• merge #69
• merge #107 (both are valid, why not merge?)
• merge #118

[jimmywarting]

• ESM