fix new Clang 20 Waring -Wdeprecated-literal-operator

[SvenJo]

(remove space between "" and _)

new Clang 20 compiler warning: -Wdeprecated-literal-operator

Generate warning (and with -Werror errors) like:

/home/sven/src/json/include/tao/json/binary.hpp:94:57: error: identifier '_binary' preceded by whitespace in a literal operator declaration is deprecated [-Werror,-Wdeprecated-literal-operator]
   94 |       [[nodiscard]] std::vector< std::byte > operator"" _binary()
      |                                              ~~~~~~~~~~~^~~~~~~
      |                                              operator""_binary

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.99%. Comparing base (3d1d4fc) to head (908869b).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #160      +/-   ##
==========================================
- Coverage   74.01%   73.99%   -0.03%     
==========================================
  Files         257      257              
  Lines        9191     9191              
  Branches      804      808       +4     
==========================================
- Hits         6803     6801       -2     
  Misses       1785     1785              
- Partials      603      605       +2     

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[SvenJo]

Found the change in the Clang Release Notes: https://releases.llvm.org/20.1.0/tools/clang/docs/ReleaseNotes.html

The warning -Wdeprecated-literal-operator is now on by default, as this is something that WG21 has shown interest in removing from the language. The result is that anyone who is compiling with -Werror should see this diagnostic. To fix this diagnostic, simply removing the space character from between the operator"" and the user defined literal name will make the source no longer deprecated. This is consistent with CWG2521 https://cplusplus.github.io/CWG/issues/2521.html_.

// Now diagnoses by default.
unsigned operator"" _udl_name(unsigned long long);
// Fixed version:
unsigned operator""_udl_name(unsigned long long);