Allow tilde in patterns

[xNoga]

This pull request makes a minor update to pattern parsing by allowing the tilde character ~ in patterns. It also adds a corresponding test to ensure this new behavior is covered.

• Pattern Parsing Update:

  • Allowed the tilde character ~ as a valid pattern character in the isPatternChar function in parse.go.

• Testing:

  • Added a test case in parse_test.go to verify that patterns containing ~ are parsed correctly.

Reference: Same as https://github.com/hmarr/codeowners/issues/37. Also, the tilde character is accepted by GitHub CODEOWNERS format.