Accept the tests Deno.* count from #15202 in the runtime boundary baseline

#15202 adds four Deno.* calls in tests/unit/zip.test.ts (Deno.mkdirSync x2,
Deno.copyFileSync, Deno.readTextFileSync) to build its unicode zip fixture.
Its PR run reported them as warnings asking for the count to be accepted
before merging, but the baseline was not updated, so main has failed the
Runtime Boundary job since 55a313c.

These calls have no deno_ral equivalent yet (fs/temp helpers arrive with
PR 09 of the runtime migration), so the increase is accepted with
--update-baseline --accept-increase. Only the tests scope changes:
870 -> 874.

Author: cderv

tools/runtime-boundary-baseline.json

@@ -16,7 +16,7 @@
     "stdImportFiles": 3
   },
   "tests": {
-    "denoCalls": 870,
+    "denoCalls": 874,
     "stdImportFiles": 176
   }
 }