Restrict conda-forge compilers for CI jobs

[ndevenish]

The generation on Clang 14 appears to be incorrect for this combination of boost, python. In particular, in

dxtbx/src/dxtbx/boost_python/ext.cpp

Lines 196 to 198 in 23f28ff

	void init_module() {
	using namespace boost::python;
	def("read_uint8", read_uint8, (arg("file"), arg("count")));

, the generated assembly appears to early-call _Py_Dealloc near the top of the function without any kind of zero protections or checks:

    0x101c03be8 <+40>:   lea    rbx, [rip + 0x7d78]       ; "file"
    0x101c03bef <+47>:   mov    qword ptr [rbp - 0x88], rbx
    0x101c03bf6 <+54>:   mov    qword ptr [rbp - 0x30], 0x0
    0x101c03bfe <+62>:   lea    r12, [rip + 0x7d67]       ; "count"
    0x101c03c05 <+69>:   mov    qword ptr [rbp - 0x38], r12
    0x101c03c09 <+73>:   xorps  xmm0, xmm0
    0x101c03c0c <+76>:   movups xmmword ptr [rbp - 0x60], xmm0
    0x101c03c10 <+80>:   mov    qword ptr [rbp - 0x50], 0x0
    0x101c03c18 <+88>:   mov    qword ptr [rbp - 0x68], rbx
    0x101c03c1c <+92>:   call   0x101c0a63c               ; symbol stub for: _Py_Dealloc
    0x101c03c21 <+97>:   mov    qword ptr [rbp - 0x60], 0x0
    0x101c03c29 <+105>:  mov    qword ptr [rbp - 0x58], r12
    0x101c03c2d <+109>:  call   0x101c0a63c               ; symbol stub for: _Py_Dealloc

Whereas on clang 13 the calls to Dealloc are later, and include zero-protection around the calls (to _Py_Dealloc and the class destructors):

    0x101c03e85 <+197>:  mov    rdi, qword ptr [rbp - 0x50]
    0x101c03e89 <+201>:  test   rdi, rdi
    0x101c03e8c <+204>:  je     0x101c03e98               ; <+216> [inlined] boost::python::handle<_object>::~handle() + 19 at handle.hpp:183
    0x101c03e8e <+206>:  dec    qword ptr [rdi]
    0x101c03e91 <+209>:  jne    0x101c03e98               ; <+216> [inlined] boost::python::handle<_object>::~handle() + 19 at handle.hpp:183
    0x101c03e93 <+211>:  call   0x101c0a6bc               ; symbol stub for: _Py_Dealloc
    0x101c03e98 <+216>

I am unsure if this difference is coming from the compiler, or from the newer build of python associated with this compiler that conda-forge selects when constraining the compiler. In any case, constraining the compiler works for now and hopefully the problem will be fixed before this becomes a problem.

[codecov]

Codecov Report

Merging #554 (24dc7ca) into main (23f28ff) will not change coverage.
The diff coverage is n/a.

❗ Current head 24dc7ca differs from pull request most recent head b1b01c7. Consider uploading reports for the commit b1b01c7 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #554   +/-   ##
=======================================
  Coverage   40.85%   40.85%           
=======================================
  Files         176      176           
  Lines       15613    15613           
  Branches     2818     2818           
=======================================
  Hits         6378     6378           
  Misses       8666     8666           
  Partials      569      569           

[ndevenish]

This looks like it's a compiler-specific issue?