Related: https://github.com/emersion/go-webdav/issues/68

https://github.com/jtagcat/calredact/blob/6c12f21a34d440c4633859c171da24d62495eed3/main.go#L106-L115
Tested faulty with fastmail.com (Cyrus). Same generated request works (207) on OX App Suite and Nextcloud.

Code in question: https://github.com/jtagcat/calredact/blob/6c12f21a34d440c4633859c171da24d62495eed3/main.go#L106-L115

Response for go-webdav on fastmail.com:
```
HTTP/1.1 400 Bad Request
Server: nginx
Date: Mon, 08 Jul 2024 18:25:32 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 491
Connection: keep-alive
Vary: Accept-Encoding
X-Frontend: frontend1
X-Trace-Id: ti_72b00284f07bc0d6f468732a01304fd4

400 Bad Request

Bad Request

The request was not understood by this server.

---

Cyrus-HTTP/3.11.0-alpha0-568-g843fbadbe-fm-20240701.003-g843fbadb Cyrus-SASL/2.1.27 Lib/XML2.9.10 Jansson/2.14 OpenSSL/1.1.1w Wslay/1.1.1 Zlib/1.2.11 Xapian/1.5.0 LibiCal/3.1 ICU4C/74.2 SQLite/3.34.1 Server at caldav.fastmail.com Port 2275

```

Response for patched request:
```
HTTP/1.1 207 Multi-Status
Server: nginx
Date: Mon, 08 Jul 2024 18:19:52 GMT
Content-Type: application/xml; charset=utf-8
Connection: keep-alive
Vary: Accept-Encoding, Brief, Prefer
X-Frontend: frontend1
X-Trace-Id: ti_cc0dac5f325d8344d7401cd5217ce56d
Content-Length: 648

/dav/calendars/user/calretest@fastmail.com/5B895624-3D36-11EF-B5BC-83625697A2A5/e5213f54-a17a-403f-90b5-83919b5ef783.ics



Mon, 08 Jul 2024 16:33:15 GMT
"70e4896a60aabe57ad32610e9b090bf7b5257208"

HTTP/1.1 200 OK

```

Requests (left: generated, right: patched):

It appears that the primary incompatibility is the d: and c:/:c syntax. I'm a mere consumer, not familiar with the RFCs. Is this an issue with go-webdav or Cyrus?

I based the patch on Cyrus [source](https://github.com/cyrusimap/cyrus-imapd) + proxying Thunderbird traffic as well.