Add additional type hints to the UrlHasher class

During review type hints were mentioned, and it made me take a second look to
see if I had missed any that could be easily added. This was especially
important for some of the instance variables that were added, as they are
expected to be modified if desired.

src/hash_http_content/hasher.py

@@ -94,20 +94,23 @@ def __init__(
         logging.debug("Default browser options: %s", default_browser_options)
 
         # Number of retries
-        self._retries = 3
+        self._retries: int = 3
         logging.debug("Using retry value of '%d'", self._retries)
 
         # Timeout in seconds
-        self._timeout = 5
+        self._timeout: int = 5
         logging.debug("Using request timeout limit of '%d' seconds", self._timeout)
 
-        self.__browser_options = {**default_browser_options, **browser_options}
+        self.__browser_options: Dict[str, Any] = {
+            **default_browser_options,
+            **browser_options,
+        }
         logging.debug("Using browser options: %s", self.__browser_options)
 
         self._browser: Browser = None
         self._browser_page: Page = None
-        self._default_encoding = encoding
-        self._hash_algorithm = hash_algorithm
+        self._default_encoding: str = encoding
+        self._hash_algorithm: str = hash_algorithm
 
         logging.debug("Using default encoding '%s'", self._default_encoding)
         logging.debug("Using hashing algorithm '%s'", self._hash_algorithm)
@@ -223,8 +226,10 @@ def _handle_html(self, contents: bytes, encoding: str) -> HandlerResult:
         soup: BeautifulSoup = BeautifulSoup(page_contents, "lxml")
         text_elements = soup.find_all(text=True)
         visible_text_elements = filter(self._is_visible_element, text_elements)
-        visible_text = " ".join(t.strip() for t in visible_text_elements if t.strip())
-        visible_bytes = bytes(visible_text, self._default_encoding)
+        visible_text: str = " ".join(
+            t.strip() for t in visible_text_elements if t.strip()
+        )
+        visible_bytes: bytes = bytes(visible_text, self._default_encoding)
 
         digest: str = get_hash_digest(self._hash_algorithm, visible_bytes)
 
@@ -267,7 +272,7 @@ def hash_url(self, url: str, verify: Union[bool, str] = True) -> UrlResult:
                     raise err
 
         # https://tools.ietf.org/html/rfc7231#section-3.1.1.5
-        content_type = (
+        content_type: str = (
             resp.headers.get("content-type", "application/octet-stream").strip().lower()
         )