[llvm-branch-commits] [MLIR][Python] Pass -Wno-unused-template to nanobind build (PR #221479)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/221479

As with a lot of other warnings, the nanobind build is also not clean
under -Wunused-template. This was enabled by default for clang 23
(although reverted for 23.1.1). Disable it in case it gets enabled again
and also in case anyone enables it manually.