Allow custom Wikifactory project base URL

Replace `wikifactory.com` with `example.com` in accepted project URLs
through environment variable.

Author: penyuan

oshminer/supported_platforms.py

@@ -3,14 +3,27 @@
 # SPDX-FileCopyrightText: 2022 Pen-Yuan Hsing
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
+# Python Standard Library imports
+import os
+import sys
+
+# Internal imports
 import oshminer.GitHub
 import oshminer.Wikifactory
 
+# Set Wikifactory base URL for projects
+# Looks for the `WIF_BASE_URL` environment variable, and if not found, default to: 
+# `wikifactory.com`
+# See: 
+# https://www.twilio.com/blog/environment-variables-python
+WIF_BASE_URL: str = os.environ.get("WIF_BASE_URL", "wikifactory.com")
+print(f"Wikifactory base URL: {WIF_BASE_URL}", file=sys.stderr)
+
 # Supported hosting platforms as a dictionary of their domains, which are 
 # matched to names of internal functions that construct API requests to the 
 # associated platforms.
-# `repo_urls` need to include one of these domains.
+# `repo_urls` in the request body needs to include one of these domains.
 supported_domains: dict = { 
     "github.com": oshminer.GitHub.make_GitHub_request, 
-    "wikifactory.com": oshminer.Wikifactory.make_Wikifactory_request
+    WIF_BASE_URL: oshminer.Wikifactory.make_Wikifactory_request
 }