DC-2023 decrement available slots

Author: pburkholder

content/events/2023-washington-dc/sponsor.md

@@ -83,7 +83,7 @@ The following chart outlines our standard sponsorship packages.
   </tr>
     <tr>
     <td>Available sponsorships</td>
-      <td class="yes"><s>10</s><strong>6</strong></td>
+      <td class="yes"><s>10</s><strong>4</strong></td>
       <td class="yes"><s>4</s><strong>3</strong></td>
       <td class="yes"><s>6</s><strong>3</strong></td>
   </tr>