You can either patch the binary
sudo patchelf --replace-needed libalpm.so.14 libalpm.so.15 "$(which paru)"
sudo pacman -S --needed base-devel
git clone https://aur.archlinux.org/paru-git.git
cd paru-git
makepkg -si
Or do both, patch the binary, then use it to install paru-git
(which is what i did)
It's just a bad idea in general. A better option would be to patch the binary to use 15. They both have the issue of forcing paru to work with a library it wasn't explicitly designed for, but symlinking (or copying) 15 to 14 forces the hack to be "system wide" instead of restricted to a single binary
as well, your solution is "temporary" only if you remember to fix it, vs patching which is (by default) overwritten the next time paru is updated
it "works", but it's not something i'd recommend someone else do