Try to fix several missing favicons in doc · qutip/QuantumToolbox.jl@1eb426d

removing `stable` and linking `stable` to `v0.21.4`.

removing `v0.21` and linking `v0.21` to `v0.21.4`.

removing `v0.20` and linking `v0.20` to `v0.20.0`.

removing `v0.19` and linking `v0.19` to `v0.19.1`.

removing `v0.18` and linking `v0.18` to `v0.18.0`.

removing `v0.17` and linking `v0.17` to `v0.17.0`.

removing `v0.16` and linking `v0.16` to `v0.16.0`.

removing `v0.15` and linking `v0.15` to `v0.15.0`.

removing `v0.14` and linking `v0.14` to `v0.14.1`.

removing `v0.13` and linking `v0.13` to `v0.13.1`.

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