Logo (Builtin): add z/OS

Ref: https://github.com/dylanaraps/neofetch/pull/2436

src/logo/ascii/zos.txt

@@ -0,0 +1,7 @@
+             //  OOOOOOO  SSSSSSS
+            //  OO    OO SS
+    zzzzzz //  OO    OO SS
+      zz  //  OO    OO   SSSS
+    zz   //  OO    OO       SS
+  zz    //  OO    OO       SS
+zzzzzz //   OOOOOOO  SSSSSSS

src/logo/builtin.c

@@ -4422,6 +4422,14 @@ static const FFlogo Z[] = {
         .colorKeys = FF_COLOR_FG_BLUE,
         .colorTitle = FF_COLOR_FG_BLUE,
     },
+    // Z/OS
+    {
+        .names = {"z/OS", "zos"},
+        .lines = FASTFETCH_DATATEXT_LOGO_ZOS,
+        .colors = {
+            FF_COLOR_FG_BLUE,
+        },
+    },
     // LAST
     {},
 };