build: allow for broader versions of tslib peer dependency

It's generally good practice to make peer dependencies as lenient as possible so that they
are compatible with other packages that share that same peer dependency, as mentioned
here: https://nodejs.org/en/blog/npm/peer-dependencies/

package.json

@@ -33,7 +33,7 @@
       "type guards"
    ],
    "peerDependencies": {
-      "tslib": "1.9.x"
+      "tslib": ">= 1.9.0 < 2"
    },
    "devDependencies": {
       "@silvermine/chai-strictly-equal": "1.1.0",