Update WORKSPACE

Add `rules_license`, needed by `platforms`.
diff --git a/WORKSPACE b/WORKSPACE
index 5f1d872..8f49808 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -16,6 +16,16 @@
     sha256 = "8150406605389ececb6da07cbcb509d5637a3ab9a24bc69b1101531367d89d74",
 )
 
+# `platforms` needs `rules_license` on Windows. This can be removed if `platforms` above is removed.
+http_archive(
+    name = "rules_license",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_license/releases/download/0.0.8/rules_license-0.0.8.tar.gz",
+        "https://github.com/bazelbuild/rules_license/releases/download/0.0.8/rules_license-0.0.8.tar.gz",
+    ],
+    sha256 = "241b06f3097fd186ff468832150d6cc142247dc42a32aaefb56d0099895fd229",
+)
+
 local_repository(
     name = "spirv_headers",
     path = "external/spirv-headers",