Exclude .git from Windows Python toolchain fileset

This fileset is part of the prebuilt_python3 runtime on Windows.

Fixes: 229543881
Test: manual
Change-Id: If31c1952f0d98d3da974d27dbb46614d45d06739
diff --git a/BUILD b/BUILD
index 5bce1d2..94f9b48 100644
--- a/BUILD
+++ b/BUILD
@@ -2,7 +2,10 @@
 
 filegroup(
     name = "windows-x86",
-    srcs = glob(["**"]),
+    srcs = glob(
+        include = ["**"],
+        exclude = [".git/**"]
+    ),
 )
 
 filegroup(