7.10.0->7.10.2 upgrade `thread 'main' panicked`

```
jack@Jacks-MacBook-Air-2 ~/d/app (main)> gel migrate
Newer version of gel tool exists 7.10.2+672a98b (current 7.10.0+5b86973). To upgrade run `gel cli upgrade`
Connecting to Gel instance 'app' at localhost:10700...
Legacy migration file names detected, consider running 'gel migration upgrade-format'
Everything is up to date. Revision m1whdzzg3dy6ripegsln2b3pihjakpulewqwi3kdnrlwkqoeppi73a
jack@Jacks-MacBook-Air-2 ~/d/app (main)> gel cli upgrade

thread 'main' panicked at src/portable/repository.rs:371:7:
Cannot start a runtime from within a runtime. This happens because a function (like `block_on`) attempted to block the current thread while the thread is being used to drive asynchronous tasks.
stack backtrace:
0: __rustc::rust_begin_unwind
1: core::panicking::panic_fmt
2: gel::portable::repository::get_platform_cli_packages
3: tokio::runtime::context::runtime::enter_runtime
4: gel::cli::run
5: gel::_main
6: gel::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
```

Reproduce the failure with `gel cli upgrade` using the versions and environment shown in the report. Start at `src/portable/repository.rs:371` and follow `get_platform_cli_packages` through the `gel::cli::run` path. Done means the upgrade command no longer panics and completes successfully.

Written by the indexing model from the issue text.