feat: Add update checker tooling

Add the initial dataset, version checker, tests, and project setup files so the update checker can be run and validated.

tests/test_extraction.py

@@ -0,0 +1,24 @@
+import json
+import sys
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).resolve().parents[1]))
+
+from check_updates import ExtractRule, extract_version
+
+
+def test_extract_jsonpath():
+    body = json.dumps({"version": "1.2.3"})
+    rule = ExtractRule(type="jsonpath", value="$.version")
+    assert extract_version(body, rule) == "1.2.3"
+
+
+def test_extract_header():
+    rule = ExtractRule(type="header", value="x-version")
+    headers = {"x-version": "2.3.4"}
+    assert extract_version("", rule, headers) == "2.3.4"
+
+
+def test_extract_regex_group():
+    rule = ExtractRule(type="regex", value=r"Version: (\d+\.\d+\.\d+)")
+    assert extract_version("Version: 1.9.0", rule) == "1.9.0"