fix(*): downgrade vue-tsc for type errors

[adamdehaven]

Summary

Downgrade vue-tsc to version 1.2.0 to resolve built type errors stemming from version 1.2.1

Link to opened issue: vuejs/language-tools#2714

PR Checklist

• Naming & Structure: the files and package structure use the conventions outlined in the Creating a Package docs.
• Tests pass: check the output of all package unit and/or component tests.
  • If this PR is the result of a bug, test coverage was added accordingly.
• Functional: all changes do not break existing APIs, but if so, a BREAKING CHANGE commit is in place to bump the major version.
• Conventional Commits all commits follow the conventional commit standards outlined in the main README.
• Docs: includes a technically accurate README, and the docs have been updated accordingly based on the changes in this PR.

[kaiarrowood]

LGTM!