nginx: serve ACME challenges over unencrypted HTTP (#116)

RFC 8555 section 8.3 [1] states HTTP challenge MUST be served over TCP
port 80 and while the verification follows redirects, those are unneed
and migh be harmful in specific deployment scenarios.

[1] https://datatracker.ietf.org/doc/html/rfc8555#section-8.3

Signed-off-by: Wojtek Porczyk <woju@invisiblethingslab.com>

configs/nginx/redirect-to-https.conf

@@ -1 +1,3 @@
-return 301 https://$host$request_uri;
+location / {
+	return 301 https://$host$request_uri;
+}