feat: remove usage of .sync and define explicitly emits (#10209)

References

- https://v3-migration.vuejs.org/breaking-changes/v-model
-
https://v3-migration.vuejs.org/breaking-changes/v-on-native-modifier-removed.html

app/javascript/dashboard/modules/contact/ContactMergeModal.vue

@@ -1,4 +1,5 @@
 <script>
+import { defineModel } from 'vue';
 import { useAlert, useTrack } from 'dashboard/composables';
 import MergeContact from 'dashboard/modules/contact/components/MergeContact.vue';
 
@@ -14,10 +15,11 @@ export default {
       type: Object,
       required: true,
     },
-    show: {
-      type: Boolean,
-      default: false,
-    },
+  },
+  setup() {
+    const show = defineModel('show', { type: Boolean, default: false });
+
+    return { show };
   },
   data() {
     return {
@@ -69,9 +71,8 @@ export default {
 };
 </script>
 
-<!-- eslint-disable vue/no-mutating-props -->
 <template>
-  <woot-modal :show.sync="show" :on-close="onClose">
+  <woot-modal v-model:show="show" :on-close="onClose">
     <woot-modal-header
       :header-title="$t('MERGE_CONTACTS.TITLE')"
       :header-content="$t('MERGE_CONTACTS.DESCRIPTION')"