Fix dependencies dev.nix

[WelliRigo]

Fix Firebase Studio template:

• IDX template expands to a project that doesn't build due to version issues in pub.dev #27

Its the same fix implemented at flutter codelabs: flutter/codelabs#2267.
Another alternative would be to change nixpkgs channel to unstable.

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• I listed at least one issue that this PR fixes in the description above.
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[WelliRigo]

@rodydavis