How to use k3sup join a node in control node server

I used two cloud server, e.g. A is `1.1.1.1`, B is `2.2.2.2`, they are brand new to the environment, and can be connected to each other,

```bash
# In server A
ssh -i /root/.ssh/test_150_to_43_rsa root@2.2.2.2
# In server B
ssh -i /root/.ssh/test_43_to_150_rsa root@1.1.1.1
```

In server A

```bash
export SERVER_IP=1.1.1.1
export USER=root

# Get wrong
k3sup install --ip $SERVER_IP --user $USER
# output
# Error: unable to load the ssh key with path "/root/.ssh/id_rsa": unable
# to read file: /root/.ssh/id_rsa, open /root/.ssh/id_rsa: no such file or directory

# It works
k3sup install --ip $SERVER_IP --user $USER --local
```

then I want to join server B to cluster

In server A

```bash
export AGENT_IP=2.2.2.2

k3sup join --ip $AGENT_IP --server-ip $SERVER_IP --user $USER --ssh-key /root/.ssh/test_150_to_43_rsa

# Output
# Running: k3sup join
# Server IP: 1.1.1.1
# Error: unable to connect to (server) 1.1.1.1:22 over ssh: ssh: handshake failed: ssh: unable to
# authenticate, attempted methods [none publickey], no supported methods remain
```

In server B

```bash
export AGENT_IP=2.2.2.2
export SERVER_IP=1.1.1.1
export USER=root
k3sup join --ip $AGENT_IP --server-ip $SERVER_IP --user $USER --ssh-key /root/.ssh/test_43_to_150_rsa

# Output
# Running: k3sup join
# Server IP: 1.1.1.1
# K107d91f95f6bfc5a2d0153b2b17d60abd5d20db87ceb73bbdcc4577483f6a33541::server:xxxxxxxx
# Error: unable to connect to 2.2.2.2:22 over ssh: ssh: handshake failed: ssh: unable to
# authenticate, attempted methods [none publickey], no supported methods remain
```

I don't know why 😭😭

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## Context

## Your Environment

+ k3sup 0.12.0
+ kubectl v1.23.8+k3s2
+ OS Linux Centos 7.6