fix(dev): prevent fs-fixture causing a re-run loop

Some part of the `tsx watch` mode causes it to observe file changes that
are caused by the fs-fixture tool in the test suite, leading to the test
suite running repeatedly. Ignoring the system's temporary directory
seems to at least put a bandaid on the problem.

This is unlikely to be compatible across every platform, so, suggestions
on improvements welcome.

package.json

@@ -39,7 +39,7 @@
 	"scripts": {
 		"build": "pkgroll --target=node16.19.0",
 		"test": "tsx tests",
-		"dev": "tsx watch --conditions=development tests",
+		"dev": "tsx watch --ignore /tmp --conditions=development tests",
 		"lint": "lintroll --cache .",
 		"type-check": "tsc --noEmit",
 		"prepack": "pnpm build && clean-pkg-json"