Do not try to use unset CBMC_PATCH variable

Author: tautschnig

scripts/run-kani.sh

@@ -151,7 +151,7 @@ build_kani() {
     source "kani-dependencies"
     # Check if installed versions are correct.
     if ./scripts/check-cbmc-version.py \
-            --major ${CBMC_MAJOR} --minor ${CBMC_MINOR} --patch ${CBMC_PATCH} \
+            --major ${CBMC_MAJOR} --minor ${CBMC_MINOR} \
             && ./scripts/check_kissat_version.sh; then
         echo "Dependencies are up-to-date"
     else