chore: migrate to eslint@9

Related to bpmn-io/internal-docs#1042

eslint.config.mjs

@@ -0,0 +1,51 @@
+import bpmnIoPlugin from 'eslint-plugin-bpmn-io';
+
+import babelParser from '@babel/eslint-parser';
+
+export default [
+  ...bpmnIoPlugin.configs.node.map(config => {
+    return {
+      ...config,
+      files: [
+        'karma.conf.js',
+        '**/test/**/*.js'
+      ]
+    };
+  }),
+  ...bpmnIoPlugin.configs.mocha.map(config => {
+    return {
+      ...config,
+      files: [
+        '**/test/**/*.js'
+      ]
+    };
+  }),
+  {
+    languageOptions: {
+      globals: {
+        sinon: true
+      },
+    },
+    files: [
+      '**/test/**/*.js'
+    ]
+  },
+
+  // hook up babel parser
+  {
+    files: [ '**/*.js', '**/*.mjs' ],
+    languageOptions: {
+      parser: babelParser,
+      parserOptions: {
+        requireConfigFile: false,
+        babelOptions: {
+          babelrc: false,
+          configFile: false,
+          plugins: [
+            '@babel/plugin-syntax-import-attributes'
+          ]
+        },
+      }
+    }
+  }
+];