Fix push! for VarNamedVector

This should have been changed in #940, but slipped through as the file
wasn't listed as one of the changed files.

Author: penelopeysm

src/varnamedvector.jl

@@ -766,6 +766,11 @@ function update_internal!(
     return nothing
 end
 
+function BangBang.push!(vnv::VarNamedVector, vn, val, dist)
+    f = from_vec_transform(dist)
+    return setindex_internal!(vnv, tovec(val), vn, f)
+end
+
 # BangBang versions of the above functions.
 # The only difference is that update_internal!! and insert_internal!! check whether the
 # container types of the VarNamedVector vector need to be expanded to accommodate the new