[2.077] Remove runnable examples blacklist

[wilzbach]

With 2.077 all public examples in Phobos are runnable and thus we can
finally remove the blacklist.

As 2.077 is around the corner, this can be merged fairly soon :)

[dlang-bot]

Thanks for your pull request, @wilzbach!

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[wilzbach]

For reference, the final PR to make all public examples in Phobos runnable as standalone was dlang/phobos#5607

[wilzbach]

As 2.077.0 has been published three weeks ago, this is more than ready to be merged.
CC @JackStouffer @ZombineDev