Upgrade Deno to 2.6.3

Author: dahlia

.github/actions/setup-deno/action.yaml

@@ -6,4 +6,4 @@ runs:
   steps:
   - uses: denoland/setup-deno@v2
     with:
-      deno-version: 2.5.6  # Keep in sync with mise.toml
+      deno-version: 2.6.3  # Keep in sync with mise.toml

mise.toml

@@ -2,6 +2,6 @@
 # Bun version should be kept in sync with GitHub Actions workflows
 bun = "1.2.22"
 # Deno version should be kept in sync with GitHub Actions workflows
-deno = "2.5.6"
+deno = "2.6.3"
 node = "22"
 "npm:pnpm" = "latest"