cannot link libpq on Mac M1

I've been trying to run the Rust Diesel crate on my Macbook M1 and it doesn't work. The final part of the compilation gets broken by the following error:

  = note: ld: warning: ignoring file /usr/local/Cellar/libpq/14.1/lib/libpq.dylib, building for macOS-arm64 but attempting to link with file built for macOS-x86_64
          Undefined symbols for architecture arm64:

When I get the info for libpq I get the following:

maxwellflitton@Maxwells-MacBook-Pro vanguard % brew info libpq                                                           
libpq: stable 14.1 (bottled) [keg-only]
Postgres C API library
https://www.postgresql.org/docs/14/libpq.html
/usr/local/Cellar/libpq/14.1 (2,335 files, 27.8MB)
  Poured from bottle on 2022-01-09 at 00:14:32
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/libpq.rb
License: PostgreSQL
==> Dependencies
Required: krb5 ✔, [email protected] ✔
==> Caveats
libpq is keg-only, which means it was not symlinked into /usr/local,
because conflicts with postgres formula.

If you need to have libpq first in your PATH, run:
  echo 'export PATH="/usr/local/opt/libpq/bin:$PATH"' >> ~/.zshrc

For compilers to find libpq you may need to set:
  export LDFLAGS="-L/usr/local/opt/libpq/lib"
  export CPPFLAGS="-I/usr/local/opt/libpq/include"

I've tried installing with the following command:

RUSTFLAGS='-L /usr/local/Cellar/libpq/14.1/lib' cargo install diesel_cli --no-default-features --features postgres --force

But I still get the same error. Will it just be easier to wipe the whole thing and start again and if so how would I do this? Other people on the internet using the M1 seem to be able to get round the problem with a simple brew install libpq. Never had any issues with my previous intel mac. My ~/.cargo/config.toml has the following configuration:

[target.aarch64-apple-darwin]
rustflags = '-L /usr/local/Cellar/libpq/14.1/lib -L /opt/homebrew/lib'

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