Use zinc everywhere

lib/music_library_web/controllers/session_html/new.html.heex

@@ -1,7 +1,7 @@
 <div class="flex min-h-full items-center justify-center px-4 py-12 sm:px-6 lg:px-8">
   <div class="w-full max-w-sm space-y-10">
     <div>
-      <h2 class="mt-10 text-center text-2xl font-bold leading-9 tracking-tight text-gray-900 dark:text-gray-200">
+      <h2 class="mt-10 text-center text-2xl font-bold leading-9 tracking-tight text-zinc-900 dark:text-zinc-200">
         <%= gettext("Welcome to your Music Library") %>
       </h2>
     </div>
@@ -19,10 +19,10 @@
               "relative block w-full rounded-md border-0 py-1.5",
               "sm:text-sm sm:leading-6",
               "ring-1 ring-inset focus:z-10 focus:ring-2 focus:ring-inset",
-              "text-gray-900 dark:text-gray-200",
+              "text-zinc-900 dark:text-zinc-200",
               "dark:bg-zinc-700",
-              "ring-gray-200 dark:ring-gray-400",
-              "placeholder:text-gray-400 dark:placeholder:text-gray-400",
+              "ring-zinc-200 dark:ring-zinc-400",
+              "placeholder:text-zinc-400 dark:placeholder:text-zinc-400",
               "focus:ring-zinc-400 dark:focus:ring-zinc-300"
             ]}
             placeholder="Password"
@@ -37,7 +37,7 @@
             "flex w-full justify-center rounded-md",
             "bg-zinc-900 hover:bg-zinc-700 dark:bg-zinc-100 dark:hover:bg-zinc-400",
             "px-3 py-1.5 text-sm font-semibold leading-6",
-            "text-white dark:text-gray-900",
+            "text-white dark:text-zinc-900",
             "focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-zinc-600"
           ]}
         >