Change C-style casts to static_cast and remove unnecessary semicolons

[jmcarcell]

I have been playing a bit with some warnings in Key4hep and I get some from included files from podio. The C-style cast may be useful. I guess these don't hurt anyway.

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• Change C-style casts to static_cast and remove unnecessary semicolons

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[m-fila]

Here is another semicolon to be removed https://github.com/AIDASoft/podio/blob/df5430c7cf2cbd7982130b6247d333799aa5dca5/include/podio/DataSource.h#L95-L97 There is a clang-format check for this https://clang.llvm.org/docs/ClangFormatStyleOptions.html#removesemicolon but there is a disclaimer that it may produce incorrect code so probably we don't want to add it

Also there is a clang-tidy check for casts but it misses some cases and flags the code in MurmurHash so I guess there is little reason to add it

[jmcarcell]

For casts there is -Wold-style-cast. I added a pragma for Murmurhash3 so that it doesn't complain.

[m-fila]

Are these flags and pragmas supported by all the compilers we have?

[jmcarcell]

With all the compilers we have being GCC yes, but they also work fine with Clang.