Add optional dependencies for development and update .gitignore

- Added `.DS_Store` to `.gitignore` to prevent macOS system files from being tracked.
- Introduced optional development dependencies in `pyproject.toml`, including `pytest` and `responses`, to facilitate testing and development.
- Updated `uv.lock` with new package dependencies and versions for improved compatibility and functionality.
- Created new test files `conftest.py` and `test_view.py` to establish testing fixtures and implement unit tests for the `ModelView` class.

pyproject.toml

@@ -20,9 +20,19 @@ dependencies = [
     "ttp>=0.10.0",
 ]
 
+[project.optional-dependencies]
+dev = [
+    "pytest>=8",
+    "responses>=0.25",
+]
+
 [project.urls]
 Repository = "https://github.com/sttarsky/oxipy"
 
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+pythonpath = ["."]
+
 [tool.setuptools.packages.find]
 where = ["."]
 include = ["oxi*"]
@@ -31,4 +41,10 @@ include = ["oxi*"]
 include-package-data = true
 
 [tool.setuptools.package-data]
-"oxi" = ["**/*.ttp"]
+"oxi" = ["**/*.ttp"]
+
+[dependency-groups]
+dev = [
+    "pytest>=9.0.3",
+    "responses>=0.26.1",
+]