BUMP v1.16.0-rc1

Signed-off-by: mongodb-dbx-release-bot[bot] <167856002+mongodb-dbx-release-bot[bot]@users.noreply.github.com>

Author: mongodb-dbx-release-bot[bot]

version/version.go

@@ -8,4 +8,4 @@
 package version // import "go.mongodb.org/mongo-driver/version"
 
 // Driver is the current version of the driver.
-var Driver = "1.16.0-rc0"
+var Driver = "1.16.0-rc1"