Improve HTTP handling in scripts (#449)

Provide some helper methods to hide the complexity of parsing HTML, JSON, YAML, XML or Markdown.

src/netbsd.py

@@ -1,16 +1,14 @@
 import logging
 
-from bs4 import BeautifulSoup
 from common import dates, endoflife, http, releasedata
 
 """Fetches NetBSD versions and EOL information from https://www.netbsd.org/."""
 
 for config in endoflife.list_configs_from_argv():
     with releasedata.ProductData(config.product) as product_data:
-        response = http.fetch_url(config.url)
-        soup = BeautifulSoup(response.text, features="html5lib")
+        html = http.fetch_html(config.url)
 
-        for row in soup.select('table tbody tr'):
+        for row in html.select('table tbody tr'):
             cells = [cell.get_text(strip=True) for cell in row.select('td')]
 
             version = cells[0]