v6.0.0

6.0.0 (2021-07-05)

User-impacting

• Breaking enhancement: Create as true ESM module
• Breaking change: Utilize .cjs extension for UMD and CJS builds (very
  old browsers might not support, but needed with the change given that
  Webpack may complain if there even exists CJS within what it thinks is
  an ESM file, the ".js", our default)
• Breaking change: Utilize .js extension instead of .mjs for now default
  ESM builds

Dev-impacting

• npm: Add lint script
• npm: Update devDeps.