Bump version for v1.18.0-rc.1 release

Signed-off-by: Evan Lezar <elezar@nvidia.com>

Author: elezar

versions.mk

@@ -13,8 +13,8 @@
 # limitations under the License.
 
 LIB_NAME := nvidia-container-toolkit
-LIB_VERSION := 1.17.4
-LIB_TAG :=
+LIB_VERSION := 1.18.0
+LIB_TAG := rc.1
 
 # The package version is the combination of the library version and tag.
 # If the tag is specified the two components are joined with a tilde (~).