Syntax & Style Fixes

[NeoByteXx]

1. Regex Fix in nix_bump_pr_changes.py
   Old: r"'github:([^\/]+/[^\/]+)/([^']+)"
   New: r"'github:([^/]+/[^/]+)/([^']+)"
   Why? Removed unnecessary backslashes for cleaner regex.
2. Error Message Improvement in Shell Script
   Old: echo "Unknown option $1"
   New: echo "Unknown option: $1"
   Why? Added a colon for better readability.
3. Shell Syntax Cleanup
   Old: echo "${1}"; exit 1;
   New: echo "$1"; exit 1
   Why? Removed redundant curly braces for cleaner syntax.

[CLAassistant]

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