Change Python minimum version 3.7 -> 3.8

pyproject.toml

@@ -4,11 +4,11 @@ description="Opencv implementations of the operators and tensor of aidge framewo
 dependencies = [
     "numpy>=1.21.6",
 ]
-requires-python = ">= 3.7"
+requires-python = ">= 3.8"
 dynamic = ["version"] # defined in tool.setuptools_scm
 readme = "README.md"
 license = { file = "LICENSE" }
-classifiers = [ 
+classifiers = [
     "Development Status :: 2 - Pre-Alpha",
     "Programming Language :: Python :: 3"
     ]