[Glitch] Change admin announcement edition interface to use datetime-local

Port 9cb523d3be to glitch-soc

Co-authored-by: Eugen Rochko <eugen@zeonfederated.com>
Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/styles/forms.scss

@@ -395,6 +395,7 @@ code {
   input[type=email],
   input[type=password],
   input[type=url],
+  input[type=datetime-local],
   textarea {
     box-sizing: border-box;
     font-size: 16px;
@@ -435,7 +436,8 @@ code {
   input[type=text],
   input[type=number],
   input[type=email],
-  input[type=password] {
+  input[type=password],
+  input[type=datetime-local] {
     &:focus:invalid:not(:placeholder-shown),
     &:required:invalid:not(:placeholder-shown) {
       border-color: lighten($error-red, 12%);
@@ -451,6 +453,7 @@ code {
     input[type=number],
     input[type=email],
     input[type=password],
+    input[type=datetime-local],
     textarea,
     select {
       border-color: lighten($error-red, 12%);