Support openSUSE Tumbleweed

[ethanc8]

It would be nice to support openSUSE Tumbleweed when installing dependencies. Note that some Tumbleweed systems might have dnf or yum installed, but all systems should have zypper installed and zypper should be preferred.

[ethanc8]

After installing the dependencies according to #28, I get at the end of my gnustep-web-install run (after the build and install of gnustep-back):

================ Post Installation ================
/home/ethan/Projects/GNUstep/scripts-install/gnustep/gnustep
GNUmakefile:30: 
GNUmakefile:31: Unable to obtain GNUSTEP_MAKEFILES setting from gnustep-config!
GNUmakefile:32: Perhaps gnustep-make is not properly installed,
GNUmakefile:33: so gnustep-config is not in your PATH.
GNUmakefile:34: 
GNUmakefile:35: Your PATH is currently /home/ethan/Applications/swift-6.0.3-RELEASE-amazonlinux2/usr/bin:/home/ethan/.pixi/bin:/home/ethan/miniforge3/bin:/home/ethan/.local/bin:/home/ethan/.local/bin:/home/ethan/.local/bin:/home/ethan/micromamba/condabin:/home/ethan/.pixi/bin:/home/ethan/miniforge3/bin:/home/ethan/.local/bin:/home/ethan/bin:/usr/local/bin:/usr/bin:/bin
GNUmakefile:36: 
GNUmakefile:41: *** You need to set GNUSTEP_MAKEFILES before compiling!.  Stop.
GNUmakefile:30: 
GNUmakefile:31: Unable to obtain GNUSTEP_MAKEFILES setting from gnustep-config!
GNUmakefile:32: Perhaps gnustep-make is not properly installed,
GNUmakefile:33: so gnustep-config is not in your PATH.
GNUmakefile:34: 
GNUmakefile:35: Your PATH is currently /usr/sbin:/usr/bin:/sbin:/bin
GNUmakefile:36: 
GNUmakefile:41: *** You need to set GNUSTEP_MAKEFILES before compiling!.  Stop.
Done...

Following this, sourcing GNUstep.sh was not automatically done. I had to manually fix this by running printf "source /usr/GNUstep/System/Library/Makefiles/GNUstep.sh \n" >>~/.bashrc.