Allow EVAL_RO and EVALSHA_RO to be routed to read replica

[zakaf]

Pull Request check-list

Please make sure to review and check all of these items:

• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Was the change added to CHANGES file?

NOTE: these things are not required to open a PR and can be done
afterwards / while the PR is open.

Description of change

• fixes EVAL_RO, EVALSHA_RO doesn't get routed to replicas #2490 by adding EVAL_RO and EVALSHA_RO to READ_COMMANDS
• minor typo fix (Lue -> Lua)
• test_reading_from_replicas_in_round_robin asserts multiple GET commands getting routed to master and replica
  • two READONLY calls would only happen with 3 or more GET commands only if there are two nodes for the slot

In addition, i've tested locally using the below method

1. running MONITOR command on both the master and the replica node
2. RUN EVAL_RO and EVALSHA_RO multiple times
3. see the output of MONITOR to confirm that commands were routed in a round-robin manner

[codecov-commenter]

Codecov Report

Base: 92.22% // Head: 92.22% // Decreases project coverage by -0.00% ⚠️

Coverage data is based on head (a184119) compared to base (55298e4).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@ Coverage Diff @@ ## master #2494 +/- ## ========================================== - Coverage 92.22% 92.22% -0.01%  ========================================== Files 113 113 Lines 29380 29378 -2 ========================================== - Hits 27096 27094 -2  Misses 2284 2284 

Impacted Files	Coverage Δ
redis/commands/cluster.py	94.02% <ø> (ø)
redis/commands/core.py	82.16% <ø> (ø)
tests/test_scripting.py	93.58% <ø> (-0.09%)	⬇️
tests/test_cluster.py	97.01% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[zakaf]

@chayim i've created a PR to address #2494. If you have any concern with the PR, please let me know