also use openssl envvars to find certs on windows (closes #22449)

Patch by Christian Heimes and Alex Gaynor.
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 75bb1e0..1f0e093 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -1058,6 +1058,14 @@
         self.assertRaises(TypeError, ctx.load_default_certs, None)
         self.assertRaises(TypeError, ctx.load_default_certs, 'SERVER_AUTH')
 
+    def test_load_default_certs_env(self):
+        ctx = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+        with support.EnvironmentVarGuard() as env:
+            env["SSL_CERT_DIR"] = CAPATH
+            env["SSL_CERT_FILE"] = CERTFILE
+            ctx.load_default_certs()
+            self.assertEqual(ctx.cert_store_stats(), {"crl": 0, "x509": 1, "x509_ca": 0})
+
     def test_create_default_context(self):
         ctx = ssl.create_default_context()
         self.assertEqual(ctx.protocol, ssl.PROTOCOL_SSLv23)