make UnableToConnectToPVException less confusing

[rerpha]

Description of work

wraps PV name in single quotes so it doesn't look like we're trying to connect to a PV with a trailing colon

probably ignore ruff errors for this one they were auto fixed so i just commited them

To test

Which ticket does this PR fix?

Acceptance criteria

List the acceptance criteria for the PR

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Code Review

• Is the code of an acceptable quality?
• Are there unit tests in place? Are the unit tests small and test the a class in isolation?
• Have the changes been documented in the release notes. If so, do they describe the changes appropriately?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed.
• How do the changes handle unexpected situations, e.g. bad input?
• Has developer documentation been updated if required?

[rerpha]

sorry @KathrynBaker may need you to re-approve, i decided to fix the ruff issues in the end