Always install alpine-sdk as dependency

Since compilers and standard build tools like gcc/make are not installed by default, we should install alpine-sdk also as makedepend so those are not missing when you're trying to compile software.

Fixes #3 (closed)

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Needs testing. Seems to work fine for packages with and without makedepends

/ # install-makedepends install-makedepends
*** Installing makedepends for install-makedepends ***
Using aports (community)
Downloading https://gitlab.alpinelinux.org/alpine/aports/-/raw/master/community/install-makedepends/APKBUILD
Installing dependencies under virtual package .makedepends-install-makedepends
The following NEW packages will be installed:
  .makedepends-install-makedepends alpine-sdk binutils build-base file fortify-headers g++ gcc isl26 jansson libatomic libgomp libmagic libstdc++-dev make
  mpc1 mpfr4 musl-dev
After this operation, 212 MiB of additional disk space will be used.

/ # install-makedepends libqmi
*** Installing makedepends for libqmi ***
Using aports (community)
Downloading https://gitlab.alpinelinux.org/alpine/aports/-/raw/master/community/libqmi/APKBUILD
Installing dependencies under virtual package .makedepends-libqmi
The following NEW packages will be installed:
  .makedepends-libqmi alpine-sdk bash-completion-dev binutils brotli brotli-dev bsd-compat-headers build-base bzip2-dev cairo cairo-dev cairo-gobject
  cairo-tools docbook-xml docbook-xsl eudev eudev-dev eudev-libs eudev-openrc expat expat-dev file fontconfig fontconfig-dev fortify-headers freetype
  freetype-dev g++ gcc gettext gettext-asprintf gettext-dev gettext-envsubst gettext-libs git-perl glib-dev gobject-introspection gobject-introspection-dev
  help2man isl26 jansson kmod-libs libatomic libbsd libedit libedit-dev libfdisk libffi-dev libformw libgcrypt libgomp libgpg-error libgudev libgudev-dev
  libltdl libmagic libmbim libmbim-dev libmd libmenuw libncurses++ libpcre2-16 libpcre2-32 libpng libpng-dev libqrtr-glib libqrtr-glib-dev libsmartcols
  libstdc++-dev libtool libuuid libx11 libx11-dev libxau libxau-dev libxcb libxcb-dev libxdmcp libxdmcp-dev libxext libxext-dev libxml2 libxml2-utils
  libxrender libxrender-dev libxslt linux-headers make meson meson-pyc mpc1 mpfr4 musl-dev ncurses-dev pcre2-dev perl perl-error perl-git pixman pixman-dev
  samurai udev-init-scripts udev-init-scripts-openrc util-linux-dev util-macros xcb-proto xcb-proto-pyc xcb-util xcb-util-dev xorgproto xtrans xz zlib-dev
After this operation, 342 MiB of additional disk space will be used.
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