feat: bump version

Author: agoose77

packages/myst-cli/src/spec-version.ts

@@ -1 +1 @@
-export const SPEC_VERSION = 2;
+export const SPEC_VERSION = 3;

packages/myst-migrate/src/v3_outputs.ts

@@ -2,7 +2,7 @@ import { selectAll } from 'unist-util-select';
 import type { IFile } from './types.js';
 
 export const VERSION = 3;
-export const DATE = new Date(Date.parse('2025-04-09'));
+export const DATE = new Date(Date.parse('2025-07-30'));
 
 export const DESCRIPTION = `
 \`Output\` nodes previously could not represent AST trees for each output.