Support Unicode 15.1.0

Merge pull request #73 from shogo82148/add-go1.20

add Go 1.20, 1.19, 1.18 and 1.17 to the build matrix.

Merge pull request #65 from tty2/feature/trim-prefix

trim prefix

Merge pull request #51 from tklauser/bump-uniseg

Bump github.com/rivo/uniseg to v0.2.0

Fix narrow width: Added StrictEmojiNarrow

In EastAsianWidth, neutral always should be double-width.

Merge pull request #29 from rivo/graphemestringwidth

Fixed StringWidth() implementation by using proper Unicode grapheme cluster segmentation. Fixes #28

Merge pull request #41 from mattn/unicode13

Support Unicode13

Add go generate

Merge pull request #35 from mattn/fix-width

Fix width