fix typo in letters.h #13

	# vim: set ft=yaml ts=2 sw=2 expandtab:
	name: Test Suite
	on:
	push:
	branches:
	- master
	pull_request:
	branches:
	- master
	concurrency:
	group: ${{ github.workflow }}-${{ github.ref }}
	cancel-in-progress: true
	jobs:
	build:
	name: "Build"
	strategy:
	matrix:
	os: [ubuntu-latest, macos-latest]
	defaults:
	run:
	shell: bash
	runs-on: "${{ matrix.os }}"
	timeout-minutes: 5
	steps:
	- name: Check out code
	uses: actions/checkout@v4
	- name: Touch all code # workaround odd autoconf problems
	run: touch *
	- name: Run configure step
	run: ./configure
	- name: Build the source distribution
	run: make dist-gzip
	- name: Build the code
	run: make
	- name: Print a banner
	run: ./banner Success!
	- name: Clean up
	run: make distclean

Provide feedback