fix: update old buttons

src/app/contact/contact.component.html

src/app/contact/contact.component.scss

src/app/contact/contact.component.ts

src/app/header/header.component.html

...etter-subscription/newsletter-subscription.component.html

...sletter-subscription/newsletter-subscription.component.ts

src/app/post/components/post-list/post-list.component.html

src/app/post/components/post-list/post-list.component.scss

src/app/post/components/post-list/post-list.component.ts

src/app/shared/components/button/button.component.html

src/app/shared/components/button/button.component.scss

src/app/shared/components/button/button.component.ts