remove pkgconfig manual overrides for appimageupdatetool

unnecessary on focal and newer distros

between the time that the original armhf/arm64 PR was made and now upstream has started building some dependencies for armhf/arm64 in their own CI and publishing releases. unfortunately we cannot use these releases since appimages (even the extraction command) do not run inside of the armhf/arm64 docker container
AppImage/AppImageKit#1027

replace wget with curl (in make_appimage) due to armhf bug

https://bugs.launchpad.net/ubuntu/+source/wget/+bug/2043636

avoids needing gpgme which, in order to build, requires _FILE_OFFSET_BITS=64 which causes issues with linking to system libz.so.1

/usr/bin/ld: libzsync2_standalone.a(zsclient.cpp.o): undefined reference to symbol 'gzopen64@@ZLIB_1.2.3.3'
/usr/bin/ld: /lib/arm-linux-gnueabihf/libz.so.1: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status

AppImageCommunity/AppImageUpdate#230