Bump version to 2026.3.0-dev (#663)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bschnurr

package.json

@@ -2,7 +2,7 @@
     "name": "black-formatter",
     "displayName": "Black Formatter",
     "description": "%extension.description%",
-    "version": "2025.3.0",
+    "version": "2026.3.0-dev",
     "preview": true,
     "serverInfo": {
         "name": "Black",