main/postmarketos-initramfs: don't hard-code libz path

It's the work of the mkinitfs to fetch the library. This was initially
introduced in c7c2b2d0 and its use-case
is non-existent today as osk-sdl is gone. In addition, the mkinitfs
rework Clayton did some time ago correctly detects libraries needed for
binaries, exactly so we don't need to pull this in manually!

main/postmarketos-initramfs/00-initramfs-extra-base.files

-/usr/lib/libz.so.1
 /sbin/btrfs
 /sbin/dmsetup
 /sbin/e2fsck

main/postmarketos-initramfs/APKBUILD

@@ -2,7 +2,7 @@
 # Co-Maintainer: Clayton Craft <clayton@craftyguy.net>
 pkgname=postmarketos-initramfs
 pkgver=3.3.3
-pkgrel=2
+pkgrel=3
 pkgdesc="Base files for the postmarketOS initramfs / initramfs-extra"
 url="https://postmarketos.org"
 options="!check"  # no tests
@@ -91,7 +91,7 @@ sha512sums="
 20bc7a21f4f59548b8179c5cb1fc2b3db64eb355988bce992db3bc4075d65b4135ff9dd7d754215d0402978811494449cce476a26cda6bb2f0f8b53ae8e36bd7  00-default.modules
 9c0e8f6f61d5da191e03a1aa9d5d0ceb5baf1eae6dbb9bfb0af59817783525119ac8394b135f303f7b6434a3eab0b49185fb90379e06823db847a4999c75ce33  00-initramfs-base.dirs
 929a8e6cca6b2b4ac6af89fc3912e80315f51c9bf6e9479124ccb7ebe9e99c6c1cafb98d3aa01b0a76a2f6e0071ba3eb86c7a2169a15c2e1788d69458bea3471  00-initramfs-base.files
-bc51380728c50584794dfed7a6b2b22258b9a31fc0b1aee2e196277e9846336228e6b48ce7af5e213edcc772addaac2c9b2bb344dcbbdb72b9c548c268393c40  00-initramfs-extra-base.files
+c4ce6c9ef5b1aa8fce0937676eb68f0172474cb86f2ab9d839f327b1c58f22ed6ae2a48133dd1c04ede33324ce82f78863f68ab6e62f88b716964b3b84f0ae9e  00-initramfs-extra-base.files
 7ea2c318e3b63b84ba8eb09e31dd74cdd9c86f5f4d8970ab54bb9213930e913c09728b60d429828007ea2dbb0472fd50dc3daae2efbe307babf854e4d8ecb238  init.sh
 bb221ed9506e646f7d1def07fba3e41daf507d08fd7467b7742d27b352fea8bbf5438a53706e18fa23ccb93afad86e44d55ba50522168abb39acf797f012ca4b  init_functions.sh
 ba3275a9af788c7c782322a22a0f144d5e50e3498ea6886486a29331f23ae89cd32d500a3635cfa7cab369afba92edc18aeca64ccbf0cd589061cce23d15b46c  unudhcpd.conf