[Minor] Add missing <algorithm> include for gcc 14

This commit addresses a compilation issue when using GCC 14. According
to GCC 14's porting guide [1], some C++ Standard Library headers no
longer include other headers they used to use internally. Specifically,
<algorithm> must now be explicitly included.

[1] https://gcc.gnu.org/gcc-14/porting_to.html

See-also: https://bugs.gentoo.org/916438
Signed-off-by: Petr Vaněk <arkamar@atlas.cz>

src/libmime/mime_string.hxx

 #define RSPAMD_MIME_STRING_HXX
 #pragma once
 
+#include <algorithm>
 #include <string>
 #include <string_view>
 #include <memory>

src/libstat/backends/http_backend.cxx

 #include "libserver/mempool_vars_internal.h"
 #include "upstream.h"
 #include "contrib/ankerl/unordered_dense.h"
+#include <algorithm>
 #include <vector>
 
 namespace rspamd::stat::http {