Include support for Pascal (.pas) file types

[klmcadams]

Include support for adding license headers to Pascal (.pas) file types by adding the following code to src/reuse/comment.py:

class PascalCommentStyle(CommentStyle):
    """Pascal comment style."""

    SHORTHAND = "pas"

    SINGLE_LINE = "//"
    INDENT_AFTER_SINGLE = " "
    MULTI_LINE = MultiLineSegments("(*", "*", "*)")
    INDENT_BEFORE_MIDDLE = " "
    INDENT_AFTER_MIDDLE = " "
    INDENT_BEFORE_END = " "

Add ".pas": PascalCommentStyle, to the EXTENSION_COMMENT_STYLE_MAP.

If this is okay, I can open a pull request with this suggestion!