[DEV-8827] Fixed errors in handling phase energisation of LinearShuntCompensator instances with a grounding_terminal

[charlta]

Description

Bug fix for setting phases with a LinearShuntCompensator with a grounding_terminal

Test Steps

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Checklist

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Code

• I have performed a self review of my own code (including checking issues raised when creating the PR).
• I have added/updated unit tests for these changes, and if not I have explained why they are not necessary.
• I have commented my code in any hard-to-understand or hacky areas.
• I have handled all new warnings generated by the compiler or IDE.
• I have rebased onto the target branch (usually main).

Security

When developing applications, use following guidelines for information security considerations:

• Access to applications should be protected with security keys/tokens or usernames and passwords;
• All sessions are encrypted if possible;
• All application input is sanitised before being acted on (ie SQL statements, etc);
• Log messages, and especially client-facing ones, must be handled securely and must not leak credentials information (internal URLs, passwords, tokens).

• I have considered if this change impacts information security and made sure those impacts are handled.

Documentation

• I have updated the changelog.
  - [ ] I have updated any documentation required for these changes.

Breaking Changes

• I have considered if this is a breaking change and will communicate it with other team members by posting it on the Slack breaking-changes channel.

Non-breaking.

[ryanjcoleman]

Task linked: DEV-8827 Update Python SDK