Blowfish has been deprecated

Just running your example code and I get this at the end of the run:

```
C:\Program Files\Python37\lib\site-packages\paramiko\transport.py:219: CryptographyDeprecationWarning: Blowfish has been deprecated
"class": algorithms.Blowfish,
```

Also, I had to add in the string library and strip off the ending newline cause the test was failing.
```
Execute Command And Verify Output
[Documentation] Execute Command can be used to run commands on the remote machine.
... The keyword returns the standard output by default.
${output}= Execute Command echo ${myString}
${output} = Strip String ${output}
Log To Console ${output}
Should Be Equal ${output} ${myString}
```

Python 3.7.9

Name: robotframework
Version: 5.0.1

Name: paramiko
Version: 2.7.2

Name: scp
Version: 0.14.5

Start by running the example containing Execute Command And Verify Output with the reported Python, robotframework, paramiko, and scp versions. Inspect how the example handles command output and the Paramiko warning; done means the reported example behavior and deprecation issue are addressed without the added workaround.

Written by the indexing model from the issue text.