SSHException: Channel Closed on Execute Command

I get an **SSHException: Channel closed** exception when calling **Execute Command**. All other functions within the library work; it's only Execute Command that returns the exception. **Host**, **User**, and **Pass** are valid as I can execute the **mkdir** command outside (windows shell) of Robot without issue. The FTP server logs show nothing unusual, just the connection open/close - no warnings/exceptions.

**Using:**
- robotframework-sshlibrary=3.8.0
- python=3.9.13
- rpaframework==22.0.0

**Sample code**

```
FTP Create Folder

${HOST}= Set Variable `
${USER}= Set Variable
${PASS}= Set Variable

Open Connection ${HOST}
Login ${USER} ${PASS} delay=1
Execute Command mkdir test-folder

```

Start with the SSHLibrary Execute Command implementation and its tests, then reproduce the supplied Robot Framework example using Python 3.9.13, robotframework-sshlibrary 3.8.0, and rpaframework 22.0.0. Compare this behavior with the working Open Connection, Login, and external mkdir steps; done means the reported Channel closed failure is understood and covered by a regression test or a documented limitation.

Written by the indexing model from the issue text.