fix(cards): make buttons always attached to the bottom despite the card height

Part-of: <!34>

src/components/card/style.scss

@@ -13,7 +13,9 @@
     box-shadow: 0 3px 12px 2px rgb(0 0 0 / 20%);
     padding: var(--fw-card-padding);
     font-size: 1rem;
-    display: block;
+
+    display: flex;
+    flex-flow: column;
 
     &.is-link {
       cursor: pointer;
@@ -61,6 +63,7 @@
 
     > .card-button {
       padding-top: 30px;
+      margin-top: auto;
 
       > .funkwhale.button {
         width: 100%;