Update Conan recipe

- Apply new conventions introduced on Conan 1.8
- Removed outdated settings
- Update license to follow SPDX format

Closes #926
Closes #943

.conan/test_package/conanfile.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+from conans import ConanFile, CMake
+import os
+
+
+class TestPackageConan(ConanFile):
+    settings = "os", "compiler", "build_type", "arch"
+    generators = "cmake"
+
+    def build(self):
+        cmake = CMake(self)
+        cmake.configure()
+        cmake.build()
+
+    def test(self):
+        assert os.path.isfile(os.path.join(self.deps_cpp_info["Catch2"].rootpath, "licenses", "LICENSE.txt"))
+        bin_path = os.path.join("bin", "test_package")
+        self.run("%s -s" % bin_path, run_environment=True)