Yes, this is a cleric spell for you.
From the Cleric Domains class ability
Your choice grants you domain spells and other features when you choose it at 1st level. It also grants you additional ways to use Channel Divinity when you gain that feature at 2nd level, and additional benefits at 6th, 8th, and 17th levels.
Each domain has a list of spells-its domain spells that you gain at the cleric levels noted in the domain description. Once you gain a domain spell, you always have it prepared, and it doesn't count against the number of spells you can prepare each day.
If you have a domain spell that doesn't appear on the cleric spell list, the spell is nonetheless a cleric spell for you.
And from the Death Domain
At 1st level, you learn one necromancy cantrip of your choice from any spell list. When you cast a necromancy cantrip that normally targets only one creature, the spell can instead target two creatures within range and within 5 feet of each other.
I would say that this makes it a Domain spell, which by extension makes it a Cleric spell for you, and would then use your Wisdom bonus for casting.
Besides, as @Xirema has pointed out, what stat would you use to cast it, other than Wisdom? It's not intrinsically a "Wizard spell" or a "Warlock spell", so you can't say it just uses Intelligence or Charisma, it's just a spell that happens to be learnable by Warlocks and Wizards regularly.