refactor: use semver to parse out major version

we were previously using a zero-deps approach but now that we need to install deps for the set-version-output step, we might as well use a safer approach here.

__tests__/lib/getPkgVersion.test.ts

@@ -6,7 +6,7 @@ import { getNodeVersion, getPkgVersion } from '../../src/lib/getPkgVersion';
 
 describe('#getNodeVersion()', () => {
   it('should extract version that matches range in package.json', () => {
-    const version = parseInt(getNodeVersion(), 10);
+    const version = getNodeVersion();
     const cleanedVersion = semver.valid(semver.coerce(version));
     expect(semver.satisfies(cleanedVersion as string, pkg.engines.node)).toBe(true);
   });

src/lib/getPkgVersion.ts

@@ -1,4 +1,5 @@
 import fetch from 'node-fetch';
+import semver from 'semver';
 
 import pkg from '../../package.json';
 
@@ -11,7 +12,7 @@ const registryUrl = 'https://registry.npmjs.com/rdme';
  */
 export function getNodeVersion() {
   const { node } = pkg.engines;
-  return Array.from(node.matchAll(/\d+/g)).pop().toString();
+  return semver.minVersion(node).major;
 }
 
 /**