Did Colorado Nullify Part of the Thirteenth Amendment?

Voters in Colorado approved a change to their state constitution, in seeming contradiction with the federal constitution.

A funny thing happened in the midterm elections on Tuesday: citizens of Colorado voted by a large margin to amend their state constitution to abolish unpaid prison labor, and I applaud them for it. However, there’s one problem: This runs counter to the Thirteenth Amendment of the U.S. Constitution, which states:

“Neither slavery nor involuntary servitude, except as punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.”

Colorado voters changed the wording of their constitution from “There shall never be in this state either slavery or involuntary servitude, except as a punishment for crime, whereof the party shall have been duly convicted” (which reflects the Thirteenth Amendment) to “There shall never be in this state either slavery or involuntary servitude.”

Doesn’t this create an obvious conflict between the Colorado State Constitution and the Federal Constitution? Can a state nullify parts of the U.S. Constitution by simply removing them? Or is there some leeway (rights can be added but not taken away, for example)?

Doesn’t this violate the Supremacy Clause of the United States Constitution (Article VI, Clause 2), establishing that the Constitution, and federal laws made pursuant to it, make up the supreme law of the land?

Let’s say voters in a state amended their state constitution to prohibit women from voting, for example, which runs counter to the Nineteenth Amendment. They clearly can’t do that—right? So how can Colorado effectively repeal part of the Thirteenth Amendment?

I’m hoping someone with a better grasp of Constitutional law can explain this to me. Again, I agree with abolishing this Constitutional caveat, but I’m not sure how a state can unilaterally do something like that.