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 upgrade-mocha-dependency-6.2.2 #103
• merge Replace 'let' with 'const' #93
• merge Add jsDelivr hits badge #69
• merge fix null presentation #107 (both are valid, why not merge?)
• merge Fix README falsely claiming browser support doesn't work #118

[jimmywarting]

• ESM