Support paramiko 4 changes

[s-t-e-v-e-n-k]

Support paramiko 4

Description

RSA key support has been removed as of paramiko 4, so only import it and check if the version number is less than 4.

Status

Replace this: describe the PR status. Examples:

• done, ready for review

Checklist (tick everything that applies)

• Code linting (required, can be done after the PR checks)
• Documentation
• Tests
• ICLA (required for bigger changes)

[micafer]

@s-t-e-v-e-n-k , please review tests as they are failing.

[s-t-e-v-e-n-k]

@s-t-e-v-e-n-k , please review tests as they are failing.

I have sorted out the failures and rebased for good measure.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 81.25000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.36%. Comparing base (f3af38f) to head (4e3c975).

Files with missing lines	Patch %	Lines
libcloud/test/compute/test_ssh_client.py	85.71%	0 Missing and 2 partials ⚠️
libcloud/compute/ssh.py	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #2135      +/-   ##
==========================================
- Coverage   83.36%   83.36%   -0.00%     
==========================================
  Files         353      353              
  Lines       81906    81910       +4     
  Branches     9007     9010       +3     
==========================================
+ Hits        68278    68279       +1     
  Misses      10799    10799              
- Partials     2829     2832       +3     

Files with missing lines	Coverage Δ
libcloud/compute/ssh.py	80.66% <50.00%> (-0.19%)	⬇️
libcloud/test/compute/test_ssh_client.py	96.10% <85.71%> (-0.42%)	⬇️

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[micafer]

LGTM