Unrestrict compiler versions

Hopefully the issue requiring 947753e is gone.

This was causing errors in the CI with conflicting libc++, gcc versions.

.azure-pipelines/ci-conda-env.txt

@@ -1,10 +1,10 @@
 conda-forge::boost
 conda-forge::boost-cpp
 conda-forge::bzip2
-conda-forge::c-compiler<1.5
+conda-forge::c-compiler
 conda-forge::cctbx-base
 conda-forge::conda
-conda-forge::cxx-compiler<1.5
+conda-forge::cxx-compiler
 conda-forge::python-dateutil
 conda-forge::dials-data
 conda-forge::docutils