gel extension install [...] broken

Hello

the gel-cli seems to be broken for extensions installation. With the current CLI installers, it is not possible (to my knowledge) to revert to an older version ?

Thanks in advance !

```
> gel --version
Gel CLI 7.9.0+070b371
> uname -a
Linux [...] 6.4.0-[...] geldata/gel#1 SMP PREEMPT_DYNAMIC [...] x86_64 x86_64 x86_64 GNU/Linux
> gel project info
┌──────────────────┬────────────────────────────────────────────────────┐
│ Database │ (unavailable) │
│ Instance name │ database │
│ Project root │ [...]/database │
│ Schema directory │ [...]/database/dbschema │
└──────────────────┴────────────────────────────────────────────────────┘
> gel instance list
┌───────┬──────────┬─────────────────┬─────────────┬─────────┐
│ Kind │ Name │ Location │ Version │ Status │
├───────┼──────────┼─────────────────┼─────────────┼─────────┤
│ local │ database │ localhost:10701 │ 6.6+01d987d │ running │
└───────┴──────────┴─────────────────┴─────────────┴─────────┘
> gel info
Gel uses the following local paths:
┌─────────┬─────────────────────────────────────┐
│ Cache │ /home/[...]/.cache/edgedb/ │
│ Config │ /home/[...]/.config/edgedb/ │
│ Install │ /home/[...]/.local/bin/ │
│ Data │ /home/[...]/.local/share/edgedb/data/ │
│ Service │ /home/[...]/.config/systemd/user/ │
└─────────┴─────────────────────────────────────┘
> gel extension list
Connecting to Gel instance 'database' at localhost:10701...
┌─────────────┬─────────┐
│ Name │ Version │
├─────────────┼─────────┤
│ ai │ 1.0 │
│ graphql │ 1.0 │
│ pgvector │ 0.7 │
│ edgeql_http │ 1.0 │
│ pg_unaccent │ 1.1 │
│ pg_trgm │ 1.6 │
│ pgcrypto │ 1.3 │
│ auth │ 1.0 │
└─────────────┴─────────┘
> gel extension install postgis

thread 'main' panicked at src/portable/repository.rs:198:1:
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:
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
> gel extension install ai

thread 'main' panicked at src/portable/repository.rs:198:1:
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:
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

```

- Gel Version: 6.6+01d987d (have tried 6.9 & 6.10 for the same result)
- Gel CLI Version: 7.9.0+070b371 (cannot test another one)
- OS Version: openSUSE Leap 15.6

Steps to Reproduce:

1. gel init
2. gel extension install [any]

Start with src/portable/repository.rs around line 198 and reproduce the failure with `gel init` followed by `gel extension install [any]`. Compare the `postgis` and `ai` commands on the reported Gel CLI and server versions. Done means extension installation no longer panics and the requested extension can be installed.

Written by the indexing model from the issue text.