Also build against 2.18 release for nightly on Windows

Author: jdblischak

.github/workflows/nightly.yml

@@ -111,7 +111,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        libtiledb_version: [release-2.17, dev]
+        libtiledb_version: [release-2.18, dev]
     defaults:
       run:
         shell: cmd