annotate ext/serd/COPYING @ 295:de5dc40f1830

Include headers needed to compile with GCC 15's -std=gnu23 default

```
In file included from ../piper-vamp-cpp/vamp-json/VampJson.h:55,
                 from ../piper-vamp-cpp/vamp-server/convert.cpp:36:
../piper-vamp-cpp/vamp-support/PluginHandleMapper.h:69:13: error: ‘uint32_t’ does not name a type
   69 |     typedef uint32_t Handle;
      |             ^~~~~~~~
../piper-vamp-cpp/vamp-support/PluginHandleMapper.h:39:1: note: ‘uint32_t’ is defined in header ‘<cstdint>’; this is probably fixable by adding ‘#include <cstdint>’
   38 | #include "PluginOutputIdMapper.h"
  +++ |+#include <cstdint>
   39 |

../piper-vamp-cpp/ext/json11/json11.cpp: In function ‘void json11::dump(const std::string&, std::string&)’:
../piper-vamp-cpp/ext/json11/json11.cpp:95:32: error: ‘uint8_t’ does not name a type
   95 |         } else if (static_cast<uint8_t>(ch) <= 0x1f) {
      |                                ^~~~~~~
../piper-vamp-cpp/ext/json11/json11.cpp:25:1: note: ‘uint8_t’ is defined in header ‘<cstdint>’; this is probably fixable by adding ‘#include <cstdint>’
   24 | #include <cmath>
  +++ |+#include <cstdint>
   25 | #include <cstdlib>
```

Signed-off-by: Michel Lind <[e-mail]>

Copyright 2011-2017 David Robillard <http://drobilla.net>

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.