unnecessary double promotion generate warning.

[SvenJo]

Describe the bug
Small MPUs have limited floating point units, for this reason we avoid double promotion.
If we try to compile Catch2 in our build pipeline with -Werror and -Wdouble-promotion, the build will fail.

Expected behavior

Catch2 should compile without warnings, helpful in the embedded world.

Reproduction steps

Compile Catch with GCC 12.3.0:

/home/sven/work/Universal-LED-Driver/build-presets/EmulationDev/_deps/catch2-src/src/catch2/catch_approx.cpp: In constructor ‘Catch::Approx::Approx(double)’:
/home/sven/work/Universal-LED-Driver/build-presets/EmulationDev/_deps/catch2-src/src/catch2/catch_approx.cpp:28:57: warning: implicit conversion from ‘float’ to ‘double’ to match other operand of binary expression [-Wdouble-promotion]
   28 |     :   m_epsilon( std::numeric_limits<float>::epsilon()*100. ),

Platform information:

• OS: Linux
• Compiler+version: GCC v12.3.0
• Catch version: v3.4.0