Fix capstone 6 compatibility for ARM64 and RISC-V

[kripticni]

Capstone 6 renamed several architecture constants in its Python bindings:

• CS_ARCH_ARM64 -> CS_ARCH_AARCH64 (old name removed)
• CS_MODE_RISCVC -> CS_MODE_RISCV_C (old name still aliased in v6, but future
  versions may drop it)

This PR:

• Adds try/except fallback in arm64.py for the ARM64 / AARCH64 rename
• Adds forward-compatible try/except in riscv.py and riscv64.py for RISCVC /
  RISCV_C
• Relaxes the capstone dependency from ^5 to >=5,<7 to allow capstone 6.x

Target branch: dev

Checklist:

• This PR only contains minor fixes.
• The new code conforms to Qiling Framework naming convention.
• The imports are arranged properly.
• No extra tests are needed for this PR.
• This PR doesn't need to update Changelog.
• The target branch is dev branch.