chore: migrate code to ESM (#73)

node_modules/semver/functions/diff.js

@@ -1,23 +0,0 @@
-const parse = require('./parse')
-const eq = require('./eq')
-
-const diff = (version1, version2) => {
-  if (eq(version1, version2)) {
-    return null
-  } else {
-    const v1 = parse(version1)
-    const v2 = parse(version2)
-    const hasPre = v1.prerelease.length || v2.prerelease.length
-    const prefix = hasPre ? 'pre' : ''
-    const defaultResult = hasPre ? 'prerelease' : ''
-    for (const key in v1) {
-      if (key === 'major' || key === 'minor' || key === 'patch') {
-        if (v1[key] !== v2[key]) {
-          return prefix + key
-        }
-      }
-    }
-    return defaultResult // may be undefined
-  }
-}
-module.exports = diff