feat(esm): convert to esm (#2569)

for #2543

BREAKING CHANGE: semantic-release is now ESM-only. since it is used through its own executable, the impact on consuming projects should be minimal

BREAKING CHANGE: references to plugin files in configs need to include the file extension because of executing in an ESM context

lib/get-commits.js

@@ -1,5 +1,7 @@
-const debug = require('debug')('semantic-release:get-commits');
-const {getCommits} = require('./git');
+import debugCommits from 'debug';
+import {getCommits} from './git.js';
+
+const debug = debugCommits('semantic-release:get-commits');
 
 /**
  * Retrieve the list of commits on the current branch since the commit sha associated with the last release, or all the commits of the current branch if there is no last released version.
@@ -8,7 +10,7 @@ const {getCommits} = require('./git');
  *
  * @return {Promise<Array<Object>>} The list of commits on the branch `branch` since the last release.
  */
-module.exports = async ({cwd, env, lastRelease: {gitHead: from}, nextRelease: {gitHead: to = 'HEAD'} = {}, logger}) => {
+export default async ({cwd, env, lastRelease: {gitHead: from}, nextRelease: {gitHead: to = 'HEAD'} = {}, logger}) => {
   if (from) {
     debug('Use from: %s', from);
   } else {
@@ -20,4 +22,4 @@ module.exports = async ({cwd, env, lastRelease: {gitHead: from}, nextRelease: {g
   logger.log(`Found ${commits.length} commits since last release`);
   debug('Parsed commits: %o', commits);
   return commits;
-};
+}