cadmus-git pkgbuild - not working - very unclean buildfile

PKGBUILD

# Maintainer: sp1rit <sp1ritCS@pm.me>
pkgname=cadmus-git
pkgver=0.0.1
pkgrel=1
pkgdesc="A GUI frontend for @werman's Pulse Audio real-time noise suppression plugin "
arch=("any")
url="https://github.com/josh-richardson/cadmus/"
license=("GPL-3.0")
depends=("zlib" "python" "python-pip")
makedepends=("awk")
provides=("${pkgname%-git}")
source=("${pkgname%-git}::git+https://github.com/josh-richardson/cadmus.git")
md5sums=("SKIP") #generate with 'makepkg -g'

prepare() {
    cd "$srcdir/${pkgname%-git}"
    ls
    cat requirements.txt | sed "s/sip==4.19.8/sip==5.3.0/" > arch_reqs.txt 
    pip install -r arch_reqs.txt
}

build() {
    FBS="python $(pip show fbs | grep Location | awk '{print $2}')/fbs/__main__.py"
    echo $FBS
    cd "$srcdir/${pkgname%-git}"
    pip show fbs
    $FBS freeze
    mkdir -p target target/cadmus
    cp src/main/resources/base/librnnoise_ladspa.so target/cadmus
    $FBS installer
}

package() {
    cd "$srcdir/${pkgname%-git}"
    ls -R
}