Minor improvements to the Windows build/release process (GH-5935)

diff --git a/Tools/msi/purge.py b/Tools/msi/purge.py
index 24fdae2..a8b8f4d 100644
--- a/Tools/msi/purge.py
+++ b/Tools/msi/purge.py
@@ -50,6 +50,7 @@
     "test_d.msi",
     "test_pdb.msi",
     "tools.msi",
+    "ucrt.msi",
     "Windows6.0-KB2999226-x64.msu",
     "Windows6.0-KB2999226-x86.msu",
     "Windows6.1-KB2999226-x64.msu",