Remove terraform.languageServer.requiredVersion (#1021)

This was deprecated in 3668713 and the usage was removed in 2a38881. This no longer needs to be in the extension.

package.json

@@ -194,11 +194,6 @@
               ],
               "default": "off",
               "description": "Traces the communication between VS Code and the language server."
-            },
-            "requiredVersion": {
-              "type": "string",
-              "description": "The required version of the Language Server described as a semantic version string, for example '^2.0.1' or '> 1.0'. Defaults to latest available version.",
-              "deprecationMessage": "Deprecated: A platform specific Language Server binary will be bundled with the extension in a future release. If you wish to use a different version than the one shipped with the extension, use terraform.languageServer.pathToBinary"
             }
           },
           "default": {