Fix date picker text color (#7776)

src/components/ha-date-input.ts

@@ -11,6 +11,7 @@ documentContainer.innerHTML = `
       [part="input-field"] {
         top: 2px;
         height: 30px;
+        color: var(--primary-text-color);
       }
       [part="value"] {
         text-align: center;