net/rubygem-activestorage81: Update to 8.1.3

Changes: https://github.com/rails/rails/releases
Security: CVE-2026-33173, CVE-2026-33174, CVE-2026-33195, CVE-2026-33202, CVE-2026-33658
(cherry picked from commit 0b78c3ec33a9a1b07059a689c5375c5d8015b20a)