Split endoflife.date and releasedata models in separate files (#276)

This makes the code easier to read.

src/cgit.py

@@ -1,7 +1,7 @@
 import sys
 
 from bs4 import BeautifulSoup
-from common import dates, endoflife, http
+from common import dates, endoflife, http, releasedata
 
 """Fetches versions from repositories managed with cgit, such as the Linux kernel repository.
 Ideally we would want to use the git repository directly, but cgit-managed repositories don't support partial clone."""
@@ -10,7 +10,7 @@ METHOD = "cgit"
 
 p_filter = sys.argv[1] if len(sys.argv) > 1 else None
 for product_name in endoflife.list_products(METHOD, p_filter):
-    product = endoflife.Product(product_name)
+    product = releasedata.Product(product_name)
     product_frontmatter = endoflife.ProductFrontmatter(product.name)
     for auto_config in product_frontmatter.get_auto_configs(METHOD):
         response = http.fetch_url(auto_config.url + '/refs/tags')