[BUG] The test model_rotating fails

[yurivict]

108/140 Testing: model_rotating
108/140 Test: model_rotating
Command: "/usr/ports/math/heyoka/work/.build/test/model_rotating"
Directory: /usr/ports/math/heyoka/work/.build/test
"model_rotating" start time: Jun 14 10:35 PDT
Output:
----------------------------------------------------------

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
model_rotating is a Catch v2.13.10 host application.
Run with -? for options

-------------------------------------------------------------------------------
basic
-------------------------------------------------------------------------------
/usr/ports/math/heyoka/work/heyoka-5.0.0/test/model_rotating.cpp:41
...............................................................................

/usr/ports/math/heyoka/work/heyoka-5.0.0/test/model_rotating.cpp:100: FAILED:
  REQUIRE( E == approximately(E0) )
with expansion:
  0.9673 == 0.96730000000000005

===============================================================================
test cases:  1 |  0 passed | 1 failed
assertions: 17 | 16 passed | 1 failed

<end of output>
Test time =   0.44 sec
----------------------------------------------------------
Test Failed.
"model_rotating" end time: Jun 14 10:35 PDT
"model_rotating" time elapsed: 00:00:00
----------------------------------------------------------

Version: 5.0.0 + PR patches
Clang-16
FreeBSD 14.1

[bluescarni]

Tentative fix up at #428 .