Bug - op fails getting SSH key

Hi andi_t_1P thank you for looking into it.
I don't recall when or how this key was created possibly it was created by an older openSSH or I think it might have been created by Amazon as part of AWS EC2 deployment
looking at such problematic keys I can see that it's 2048 bit and it is in the format of

-----BEGIN RSA PRIVATE KEY-----
...
-----END RSA PRIVATE KEY-----


I can confirm that newer keys that I create in the format of "-----BEGIN OPENSSH PRIVATE KEY-----" seem to work without an issue.

with the above hint I was able to reproduce the issue using

ssh-keygen -t rsa -b 2048 -m PEM -f <filename>

which in turn leads to the following ERROR message when downloading it from OP using cli
```
[ERROR] 2023/11/27 13:54:27 unsupported key type "RSA PRIVATE KEY" passed with the PEM

```