Switch embedded icon from 128 px² to 256 px²

... and embed a GIF (v89a) icon in RPMs, but not in XPM (v3) file format!

XPM is absolutely antiquated (it describes a picture as text!), results in large file sizes (no built-in compression) and of lower image quality than GIF (though both are "8 bit colour palette plus transparency, with 24 bit colours" formats).
GIF89a is technically much more modern than XPMv3 and `rpmbuild` only accepts GIF and XPM icons!

rpm/crypto-sdcard_sbj.spec

@@ -19,7 +19,7 @@ Source:        https://github.com/Olf0/%{name}/archive/%{version}/%{name}-%{vers
 # rpmbuild (as of v4.14.1) handles the Icon tag awkwardly and in contrast to the Source tag(s):
 # It only accepts a GIF or XPM file (successfully tested GIF89a and XPMv3) in the SOURCE directory
 # (but not in the tarball)!  Hence only to be used, when the file is put there:
-# Icon:         smartmedia_mount.128x128.gif
+# Icon:         smartmedia_mount.256x256.gif
 BuildArch:     noarch
 Requires:      systemd
 Requires:      polkit