The PKGBUILD was throwing a few errors. I fixed it with the following:

_pkgname=krunner-steam
pkgname=$_pkgname-git
pkgver=r17.b86af5d
pkgrel=1
pkgdesc="Launch Steam games from Krunner"
arch=('any')
url="https://github.com/xTibor/krunner-steam.git"
license=('LGPL-2.0-or-later')
depends=('python-gobject' 'krunner' 'kservice')
makedepends=('git')
provides=("$_pkgname")
conflicts=("$_pkgname")
source=("git+$url")
sha256sums=('SKIP')

pkgver() {
    cd "$_pkgname"
    printf "r%s.%s" "$(git rev-list --count HEAD)" "$(git rev-parse --short HEAD)"
}

package() {
    cd "$_pkgname"

    # Define the installation path for the python module
    install_path="$pkgdir/usr/lib/$_pkgname"

    # Install the python source files
    install -d "$install_path"
    install -m644 src/*.py "$install_path/"
    install -m755 src/main.py "$install_path/"

    # Install the KRunner plugin metadata
    install -Dm644 krunnersteam.desktop "$pkgdir/usr/share/krunner/dbusplugins/krunnersteam.desktop"

    # Install and create the D-Bus service file, pointing to the new install path
    install -d "$pkgdir/usr/share/dbus-1/services"
    cat <<EOF > "$pkgdir/usr/share/dbus-1/services/com.github.xtibor.krunnersteam.service"
[D-BUS Service]
Name=com.github.xtibor.krunnersteam
Exec=/usr/lib/$_pkgname/main.py
EOF
}