Make releasedata.Product usable in 'with' expression (#294)

This way the writing of the JSON file is handled automatically if the update does not fail.
It pave the way to further global improvements, such as a better error handling.

src/cgit.py

@@ -10,29 +10,27 @@ METHOD = "cgit"
 
 p_filter = sys.argv[1] if len(sys.argv) > 1 else None
 for product in endoflife.list_products(METHOD, p_filter):
-    product_data = releasedata.Product(product.name)
-    for config in product.get_auto_configs(METHOD):
-        response = http.fetch_url(config.url + '/refs/tags')
-        soup = BeautifulSoup(response.text, features="html5lib")
+    with releasedata.ProductData(product.name) as product_data:
+        for config in product.get_auto_configs(METHOD):
+            response = http.fetch_url(config.url + '/refs/tags')
+            soup = BeautifulSoup(response.text, features="html5lib")
 
-        for table in soup.find_all("table", class_="list"):
-            for row in table.find_all("tr"):
-                columns = row.find_all("td")
-                if len(columns) != 4:
-                    continue
+            for table in soup.find_all("table", class_="list"):
+                for row in table.find_all("tr"):
+                    columns = row.find_all("td")
+                    if len(columns) != 4:
+                        continue
 
-                version_str = columns[0].text.strip()
-                version_match = config.first_match(version_str)
-                if not version_match:
-                    continue
+                    version_str = columns[0].text.strip()
+                    version_match = config.first_match(version_str)
+                    if not version_match:
+                        continue
 
-                datetime_td = columns[3].find_next("span")
-                datetime_str = datetime_td.attrs["title"] if datetime_td else None
-                if not datetime_str:
-                    continue
+                    datetime_td = columns[3].find_next("span")
+                    datetime_str = datetime_td.attrs["title"] if datetime_td else None
+                    if not datetime_str:
+                        continue
 
-                version = config.render(version_match)
-                date = dates.parse_datetime(datetime_str)
-                product_data.declare_version(version, date)
-
-    product_data.write()
+                    version = config.render(version_match)
+                    date = dates.parse_datetime(datetime_str)
+                    product_data.declare_version(version, date)