fix incorrect text width with newer (1.43?) Pango

Text renders wider or narrower, as if letter-spacing is set, than
it should with newer versions of Pango.

My best understanding of this problem is that around version 1.43
Pango dropped support for subpixel antialiasing because it
switched to Harbuzz for glyph postions instead of Freetype.
For some reason it still rounds the glyph positions by default.

There's no need for node-canvas to support subpixel antialiasing.
The maintainers of the Linux font stack (Behdad and Matthias) have
stated that they wont, and it's subjective, and node-canvas cannot
make any assumptions about DPI anyways.

Reading (warning: lots of drama to wade through):
- https://gitlab.gnome.org/GNOME/pango/-/issues/404
- https://gitlab.gnome.org/GNOME/pango/-/issues/463
- harfbuzz/harfbuzz#1892
- harfbuzz/harfbuzz#2394

CHANGELOG.md

@@ -11,6 +11,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 ### Fixed
 * Add missing property `canvas` to the `CanvasRenderingContext2D` type
+* Fixed glyph positions getting rounded, resulting text having a slight `letter-spacing` effect
 
 2.11.0
 ==================

src/CanvasRenderingContext2d.cc

@@ -171,6 +171,11 @@ Context2d::Context2d(Canvas *canvas) {
   _canvas = canvas;
   _context = canvas->createCairoContext();
   _layout = pango_cairo_create_layout(_context);
+
+  // As of January 2023, Pango rounds glyph positions which renders text wider
+  // or narrower than the browser. See #2184 for more information
+  pango_context_set_round_glyph_positions(pango_layout_get_context(_layout), FALSE);
+
   states.emplace();
   state = &states.top();
   pango_layout_set_font_description(_layout, state->fontDescription);

test/public/tests.js

@@ -2693,6 +2693,11 @@ tests['measureText()'] = function (ctx) {
   drawWithBBox('right', 195, 195)
 }
 
+tests['glyph advances (#2184)'] = function (ctx) {
+  ctx.font = '8px Arial';
+  ctx.fillText('A float is a box that is shifted to the left or right on the current line.', 0, 8);
+};
+
 tests['image sampling (#1084)'] = function (ctx, done) {
   let loaded1, loaded2
   const img1 = new Image()