ci: test against pinned driver commit (#4693)

Co-authored-by: Durran Jordan <[email protected]>

Author: baileympearson

.evergreen/install-mongodb-client-encryption.sh

@@ -12,6 +12,9 @@ rm -rf mongodb-client-encryption
 git clone https://github.com/mongodb-js/mongodb-client-encryption.git
 pushd mongodb-client-encryption
 
+# TODO(NODE-7218): test against latest mongodb-client-encryption
+git checkout aa61a35f5e174cd1c1e247e036093e18c88268c6
+
 node --version
 npm --version