Use std::variant instead of mapbox::util::variant (#6903)

scripts/update_dependencies.sh

@@ -12,9 +12,6 @@ set -o nounset
 OSMIUM_PATH="osmcode/libosmium"
 OSMIUM_TAG=v2.14.0
 
-VARIANT_PATH="mapbox/variant"
-VARIANT_TAG=v1.2.0
-
 SOL_PATH="ThePhD/sol2"
 SOL_TAG=v2.17.5
 
@@ -56,6 +53,6 @@ function update_subtree () {
 }
 
 ## Update dependencies
-for dep in osmium variant sol rapidjson microtar protozero vtzero fmt; do
+for dep in osmium sol rapidjson microtar protozero vtzero fmt; do
     update_subtree $dep
 done