LLVM version detection logic in configure doesn't work on macOS
## Summary
LLVM version detection logic in configure doesn't work on macOS.
The configure script calls sed with `+` for the regex repetition, but `+` is a GNU extension in basic regex mode.
Something like `[0-9]\{1,\}` should be used instead of `[0-9]\+`.
## Steps to reproduce
```
$ brew install llvm@15
$ curl -LO https://downloads.haskell.org/~ghc/9.10.1/ghc-9.10.1-aarch64-apple-darwin.tar.xz
$ tar xf ghc-9.10.1-aarch64-apple-darwin.tar.xz
$ cd ghc-9.10.1-aarch64-apple-darwin/
$ ./configure OPT="$(brew --prefix llvm@15)/bin/opt" LLC="$(brew --prefix llvm@15)/bin/llc"
...
no
configure: We only support llvm 13 upto 16 (non-inclusive) (no version found).
no
configure: We only support llvm 13 upto 16 (non-inclusive) (no version found).
...
```
## Expected behavior
The configure script should detect LLVM version on macOS.
## Environment
* GHC version used: 9.10.1
* Operating System: macOS 13
* System Architecture: AArch64
issue