Change github signin button color to black

Signed-off-by: Anil Vishnoi <vishnoianil@gmail.com>

src/app/login/githublogin.tsx

@@ -30,7 +30,7 @@ const GithubLogin: React.FC = () => {
                 </Text>
               </TextContent>
               <div className="login-container">
-                <Button variant="primary" icon={<GithubIcon />} iconPosition="left" size="lg" onClick={handleGitHubLogin}>
+                <Button variant="primary" icon={<GithubIcon />} iconPosition="left" size="lg" style={{backgroundColor: "black"}} onClick={handleGitHubLogin}>
                   Sign in with GitHub
                 </Button>
               </div>