Bump toolchains/riscv-tools/riscv-isa-sim from 824ecdf to 88fc84d

Bumps [toolchains/riscv-tools/riscv-isa-sim](https://github.com/riscv-software-src/riscv-isa-sim) from `824ecdf` to `88fc84d`.
- [Release notes](https://github.com/riscv-software-src/riscv-isa-sim/releases)
- [Commits](riscv-software-src/riscv-isa-sim@824ecdf...88fc84d)

---
updated-dependencies:
- dependency-name: toolchains/riscv-tools/riscv-isa-sim
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>