[Issue 18369] std.algorithm.skipOver should be @nogc and nothrow

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18369

--- Comment #1 from Seb <greensunny12 at gmail.com> ---
not nothrow comes from auto-decoding and their exceptions.

not @nogc comes from throwing exceptions

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