fix: upgrade @vue/language-core from 2.0.13 to 2.0.15

Snyk has created this PR to upgrade @vue/language-core from 2.0.13 to 2.0.15.

See this package in npm:
@vue/language-core

See this project in Snyk:
https://app.snyk.io/org/hawthorne001/project/7a8af600-420d-4830-8dd5-326300b0118c?utm_source=github-cloud-app&utm_medium=referral&page=upgrade-pr

packages/language-service/package.json

@@ -20,7 +20,7 @@
 		"@volar/language-service": "2.2.0-alpha.9",
 		"@volar/typescript": "2.2.0-alpha.9",
 		"@vue/compiler-dom": "^3.4.0",
-		"@vue/language-core": "2.0.13",
+		"@vue/language-core": "2.0.15",
 		"@vue/shared": "^3.4.0",
 		"@vue/typescript-plugin": "2.0.13",
 		"computeds": "^0.0.1",