migrate to pyproject.toml (PEP 621)

[fsagbuya]

Modernize python packaging as in PEP 621.

Tested with nix build .#artiq

Closes #2695

[sbourdeauducq]

I was hoping we could get rid of setuptools, which is one of the worst Python packages out there. But this is already a small improvement, I suppose.

[sbourdeauducq]

Tested with nix build .#artiq

Doesn't work for me.

error: Cannot build '/nix/store/vy8wib1cs2ychfhfjvxfmgmxvps57bk7-python3.13-artiq-9.0+unknown.beta.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/gyfxmyydwibpcq5q2hdyiligi596qpk4-python3.13-artiq-9.0+unknown.beta-dist
         /nix/store/jp4l9lmkh3p6d4j3vxfjsf99zyxs4rj7-python3.13-artiq-9.0+unknown.beta
       Last 25 log lines:
       > Running phase: qtOwnPathsHook
       > Running phase: fixupPhase
       > shrinking RPATHs of ELF executables and libraries in /nix/store/jp4l9lmkh3p6d4j3vxfjsf99zyxs4rj7-python3.13-artiq-9.0+unknown.beta
       > checking for references to /build/ in /nix/store/jp4l9lmkh3p6d4j3vxfjsf99zyxs4rj7-python3.13-artiq-9.0+unknown.beta...
       > patching script interpreter paths in /nix/store/jp4l9lmkh3p6d4j3vxfjsf99zyxs4rj7-python3.13-artiq-9.0+unknown.beta
       > stripping (with command strip and flags -S -p) in  /nix/store/jp4l9lmkh3p6d4j3vxfjsf99zyxs4rj7-python3.13-artiq-9.0+unknown.beta/lib
       > shrinking RPATHs of ELF executables and libraries in /nix/store/gyfxmyydwibpcq5q2hdyiligi596qpk4-python3.13-artiq-9.0+unknown.beta-dist
       > checking for references to /build/ in /nix/store/gyfxmyydwibpcq5q2hdyiligi596qpk4-python3.13-artiq-9.0+unknown.beta-dist...
       > patching script interpreter paths in /nix/store/gyfxmyydwibpcq5q2hdyiligi596qpk4-python3.13-artiq-9.0+unknown.beta-dist
       >
       > Builder called die: Cannot wrap '/nix/store/jp4l9lmkh3p6d4j3vxfjsf99zyxs4rj7-python3.13-artiq-9.0+unknown.beta/bin/artiq_dashboard' because it is not an executable file
       > Backtrace:
       > 10 assertExecutable /nix/store/wxjcx5fis4bygw7bywg2jkjs4cliw3jd-make-binary-wrapper-hook/nix-support/setup-hook
       > 227 wrapProgramShell /nix/store/6l9mndwn2z52njn5shabyqc3jr3bxmla-make-shell-wrapper-hook/nix-support/setup-hook
       > 261 wrapProgram /nix/store/s3w5m3spa1g71hx0yb82lvk6394j3w5j-stdenv-linux/setup
       > 49 wrapQtApp /nix/store/fhkrkqxys2r2kvlljka3jrkw33rq3vbq-wrap-qt6-apps-hook/nix-support/setup-hook
       > 260 _callImplicitHook /nix/store/s3w5m3spa1g71hx0yb82lvk6394j3w5j-stdenv-linux/setup
       > 276 _eval /nix/store/s3w5m3spa1g71hx0yb82lvk6394j3w5j-stdenv-linux/setup
       > 215 runHook /nix/store/s3w5m3spa1g71hx0yb82lvk6394j3w5j-stdenv-linux/setup
       > 1651 fixupPhase /nix/store/s3w5m3spa1g71hx0yb82lvk6394j3w5j-stdenv-linux/setup
       > 1756 runPhase /nix/store/s3w5m3spa1g71hx0yb82lvk6394j3w5j-stdenv-linux/setup
       > 1797 genericBuild /nix/store/s3w5m3spa1g71hx0yb82lvk6394j3w5j-stdenv-linux/setup
       > 1 source /nix/store/shkw4qm9qcw5sc5n1k5jznc83ny02r39-default-builder.sh
       > 3 main /nix/store/l622p70vy8k5sh7y5wizi5f2mic6ynpg-source-stdenv.sh
       >