Bump install.sh / install.ps1 pin to unsloth>=2026.8.7

[danielhanchen]

Summary

• PyPI release unsloth 2026.8.7 is now live.
• Bumps the pinned floor in install.sh and install.ps1 from unsloth>=2026.8.6 to unsloth>=2026.8.7 so fresh installs resolve to the new wheel.
• Updates all 5 install commands in each of install.sh and install.ps1 (migrated no-torch / migrated / no-torch / local / auto torch backend paths).
• Tagged on main as v0.1.524-beta.

Follows the same pattern as #5716 and #8038.

Note on unsloth-zoo

The unsloth-zoo floor stays at unsloth-zoo>=2026.8.5 this round. That is already the latest unsloth-zoo on PyPI and matches the unsloth_zoo>=2026.8.5 floor declared in pyproject.toml, so only the unsloth half of those lines moves.

Scope

• Only the 5 base-install unsloth specs in each script change.
• The --reinstall-package / --upgrade-package flags and the unsloth-zoo @ git+https://... git-main overlay lines are untouched.

Checks

• bash -n install.sh passes.
• install.ps1 parses with 0 syntax errors via [System.Management.Automation.Language.Parser]::ParseFile.
• No stale unsloth>=2026.8.6 specs remain in either script.

Test plan

• Sanity-run install.sh on a clean Linux host
• Sanity-run install.ps1 on a clean Windows host
• Confirm uv pip install "unsloth>=2026.8.7" resolves cleanly