`using PyPlot` crashes package precompilation on Julia v1.10.0-beta1

[This is also cross-posted on PyPlot https://github.com/JuliaPy/PyPlot.jl/issues/572 - if it is not useful here pls close it]

Consider the following package:
```
(@v1.10) pkg> generate Test1
Generating project Test1:
Test1\Project.toml
Test1\src\Test1.jl
```
Where `PyPlot` has been added via `Pkg.add` to dependencies and `Test1.jl` contains
```
module Test1
using PyPlot
end
```

In that case `using Test1` (after `Pkg.activate`) goes into an endless loop (I pressed Ctrl+C at some point):
```
julia> using Test1
Precompiling Test1
Progress [> ] 0/1
◑ Test1 Waiting for background task / IO / timer. Interrupt to inspect
Interrupted: Exiting precompilation...

1 dependency had warnings during precompilation:
┌ Test1 [ddca8587-cad1-46e2-86b4-b726afea1d60]
│ [pid 7156] waiting for IO to finish:
│ TYPE[FD/PID] @UV_HANDLE_T->DATA
│ timer @00000228c312eca0->00000228bf815db0
└
```

When this is run on a fresh Julia installation it seemed that it additionally tries to install matplotlib via Conda (regardless of the fact that it is already present due to PyPlot being built earlier).

Tested on Julia 1.10 beta1, Windows11 as well Linux by myself and @giordano

Reproduce the issue with the generated Test1 package, its Test1.jl entry point, and `using PyPlot` on Julia 1.10.0-beta1. Observe the precompilation hang and any unexpected matplotlib installation on a fresh environment. Done means the package precompiles and loads without hanging, while retaining the reported PyPlot setup.

Vom Indexierungsmodell aus dem Issue-Text verfasst.