Pin epicscorelibs version to fix dependency errors

Required due to dependency version conflicts:
 aioca 1.3 requiring epicscorelibs>=7.0.3.99.4.0
 p4p 3.5.4 requiring epicscorelibs<7.0.6.99.2 and >=7.0.6.99.1.0

 p4p does have pre-release versions in the 4.0* stream, so this issue
may  fix itself once those become full releases

Author: AlexanderWells-diamond

pyproject.toml

@@ -1,3 +1,3 @@
 [build-system]
-requires = ["setuptools", "wheel", "setuptools_dso>=2.1", "epicscorelibs>=7.0.6.99.1.0"]
+requires = ["setuptools", "wheel", "setuptools_dso>=2.1", "epicscorelibs==7.0.6.99.1.0"]
 build-backend = "setuptools.build_meta:__legacy__"