Add Nix flake

[rupurt]

As a Nix user I would like to use arroyo from a Nix flake So that I can use the native binary builds But I'm currently getting a build failure on main

warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Wcpp]
    422 | #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
        |    ^~~~~~~
  In file included from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/bits/libc-header-start.h:33,
                   from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/math.h:27,
                   from include/jemalloc/internal/jemalloc_internal_decls.h:4,
                   from include/jemalloc/internal/jemalloc_preamble.h:5,
                   from src/sc.c:1:
  /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/features.h:422:4: warning: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Wcpp]
    422 | #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
        |    ^~~~~~~
  In file included from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/bits/libc-header-start.h:33,
                   from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/math.h:27,
                   from include/jemalloc/internal/jemalloc_internal_decls.h:4,
                   from include/jemalloc/internal/jemalloc_preamble.h:5,
                   from src/sec.c:1:
  /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/features.h:422:4: warning: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Wcpp]
    422 | #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
        |    ^~~~~~~
  src/malloc_io.c: In function 'buferror':
  src/malloc_io.c:107:16: error: returning 'char *' from a function with return type 'int' makes integer from pointer without a cast [-Wint-conversion]
    107 |         return strerror_r(err, buf, buflen);
        |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
  In file included from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/bits/libc-header-start.h:33,
                   from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/math.h:27,
                   from include/jemalloc/internal/jemalloc_internal_decls.h:4,
                   from include/jemalloc/internal/jemalloc_preamble.h:5,
                   from src/sz.c:1:
  /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/features.h:422:4: warning: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Wcpp]
    422 | #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
        |    ^~~~~~~
  In file included from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/bits/libc-header-start.h:33,
                   from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/math.h:27,
                   from include/jemalloc/internal/jemalloc_internal_decls.h:4,
                   from include/jemalloc/internal/jemalloc_preamble.h:5,
                   from src/stats.c:1:
  /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/features.h:422:4: warning: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Wcpp]
    422 | #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
        |    ^~~~~~~
  make: *** [Makefile:480: src/malloc_io.sym.o] Error 1
  make: *** Waiting for unfinished jobs....
  In file included from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/bits/libc-header-start.h:33,
                   from /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/math.h:27,
                   from include/jemalloc/internal/jemalloc_internal_decls.h:4,
                   from include/jemalloc/internal/jemalloc_preamble.h:5,
                   from src/tcache.c:1:
  /nix/store/pz6jgrfqyl2il2785a75vmwdp9vypv0j-glibc-2.40-66-dev/include/features.h:422:4: warning: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Wcpp]
    422 | #  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
        |    ^~~~~~~

  thread 'main' panicked at /build/arroyo-v0.15.0-dev-vendor/tikv-jemalloc-sys-0.6.0+5.3.0-1-ge13ca993e8ccb9ba9847cc330696e02839f328f7/build.rs:388:9:
  command did not execute successfully: cd "/build/source/target/release/build/tikv-jemalloc-sys-00dcf067d6321337/out/build" && "make" "-j" "48"
  expected success, got: exit status: 2
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace