Fix libxml2 related deprecated issues

[airween]

what

This PR fixes libxml2 related deprecated warnings.

why

With newest clang and gcc compilers and newest libxml2 library there were a few deprecated warnings.

In file included from msc_xml.h:23,
                 from modsecurity.h:42,
                 from re.h:38,
                 from re.c:17:
/usr/include/libxml2/libxml/SAX.h:15:4: warning: #warning "libxml/SAX.h is deprecated" [-Wcpp]
   15 |   #warning "libxml/SAX.h is deprecated"
      |    ^~~~~~~

and

msc_crypt.c: In function 'inject_hashed_response_body':
msc_crypt.c:1109:5: warning: 'name' is deprecated [-Wdeprecated-declarations]
 1109 |     new_ct = (char*)apr_psprintf(msr->mp, "text/html;%s",handler->name);
      |     ^~~~~~
In file included from /usr/include/libxml2/libxml/parser.h:25,
                 from /usr/include/libxml2/libxml/tree.h:17,
                 from modsecurity.h:22:
/usr/include/libxml2/libxml/encoding.h:169:11: note: declared here
  169 |     char *name XML_DEPRECATED_MEMBER;
      |           ^~~~

[sonarqubecloud]

Quality Gate failed

Failed conditions
B Maintainability Rating on New Code (required ≥ A)

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