Convert to ESM module (#48)

This converts the package to generate an ESM module as the build output. The instigator was #39  but there were a number of ESM-only packages in the dependencies. The final result is as follows:
* Switched from `term-size` to `terminal-size` and upgraded `ansi-regex`, `chalk` and `diff`.
* Switched to [shikiji](https://github.com/antfu/shikiji) and patched the perf optimization for `setTheme` from shiki.
* Update min node version to 18.
* There's a ~35ms improvement in startup time.
* Switched from `yarn` to `npm`. `yarn v4` does pretty weird things that were hard to get to work esp on windows.

.github/workflows/main.yml

@@ -9,20 +9,12 @@ jobs:
         runs-on: ${{ matrix.os }}
         strategy:
             matrix:
-                node_version: ['14', '16', '18', '19']
+                node_version: ['18', '19', '20']
                 os: [ubuntu-latest, windows-latest, macOS-latest]
         steps:
-            - uses: actions/checkout@v2
-            - uses: actions/setup-node@v2
+            - uses: actions/checkout@v4
+            - uses: actions/setup-node@v4
               with:
                   node-version: ${{ matrix.node_version }}
-            - name: Cache dependencies
-              uses: actions/cache@v2
-              with:
-                  path: ./node_modules
-                  key: npm-${{ hashFiles('yarn.lock') }}-${{ matrix.os }}-${{ matrix.node_version }}
-                  restore-keys: npm-
-            - name: Install dependencies
-              if: steps.cache.outputs.cache-hit != 'true'
-              run: yarn install --frozen-lockfile
-            - run: yarn test
+            - run: npm install --frozen-lockfile
+            - run: npm test

.node-version

@@ -1 +1 @@
-v14.21.2
+v18.18.2

jest.config.js

@@ -1,7 +1,8 @@
-module.exports = {
+/** @type {import('jest').Config} */
+const jestConfig = {
+    preset: 'ts-jest/presets/default-esm',
     roots: ['<rootDir>/src'],
     testMatch: ['**/?(*.)+(spec|test).+(ts|tsx|js)'],
-    transform: {
-        '^.+\\.(ts|tsx)$': 'ts-jest',
-    },
 };
+
+export default jestConfig;