Remove Windows from BCR presubmit (#121)

Windows doesn't actually pass presubmits, so this is just a lie. I would
love to fix it, but it's more important to get another release out with
the new workflow first.

This is caused by #120 which we should try to rectify sometime...

Author: jchadwick-buf

.bcr/presubmit.yml

@@ -1,7 +1,7 @@
 bcr_test_module:
   module_path: "examples/bzlmod"
   matrix:
-    platform: ["debian10", "macos", "ubuntu2004", "windows"]
+    platform: ["debian10", "macos", "ubuntu2004"]
     bazel: [7.x, 8.x]
   tasks:
     run_tests: