Add openapi spec validation and build integartion

tests/test_openapi.py

@@ -0,0 +1,20 @@
+import importlib.resources
+
+import openapi_spec_validator
+import ruamel.yaml
+
+from imagemuck import __about__
+
+
+yaml = ruamel.yaml.YAML(typ="safe")  # pylint: disable=invalid-name
+
+
+def test_openapi():
+    openapi_spec_validator.validate_spec(
+        yaml.load(importlib.resources.read_text("imagemuck", "openapi.yaml"))
+    )
+
+
+def test_openapi_version():
+    spec = yaml.load(importlib.resources.read_text("imagemuck", "openapi.yaml"))
+    assert spec["info"]["version"] == __about__.__version__