chore: bump dependencies (#30)

Upgrades ESLint dependencies, typescript and the test runner.

We have to set `concurrency` to `1` since chrome will no longer fire
visiblity changes on the document if it is in a background tab (which it
will be if the test runner runs multiple tests in parallel).

eslint.config.js

@@ -0,0 +1,23 @@
+import eslintjs from '@eslint/js';
+import {configs as tseslintConfigs} from 'typescript-eslint';
+
+const {configs: eslintConfigs} = eslintjs;
+
+export default [
+  {
+    ...eslintConfigs.recommended,
+    files: ['src/**/*.ts'],
+  },
+  ...tseslintConfigs.strict,
+  {
+    rules: {
+      '@typescript-eslint/no-unused-vars': 'off'
+    }
+  },
+  {
+    files: ['src/test/**/*.ts'],
+    rules: {
+      '@typescript-eslint/no-non-null-assertion': 'off'
+    }
+  }
+];