Downgrade vscode-languageclient to v8.1.0

Because v9.0.0 upped the VS Code requirement to v1.82.0, above our own
current requirement (and also is _very_ new). Downgrading brings its
minimum back to 1.67.0, below ours.

Author: andyleejordan

package-lock.json

@@ -79,7 +79,7 @@
     "semver": "7.5.4",
     "untildify": "4.0.0",
     "uuid": "9.0.1",
-    "vscode-languageclient": "9.0.0",
+    "vscode-languageclient": "8.1.0",
     "vscode-languageserver-protocol": "3.17.5"
   },
   "devDependencies": {