Update Unifont from v15.0.03 to v15.0.06

This also includes the v15.0.04 and v15.0.05 updates.

## 4 June 2023 (Unifont 15.0.06)
- **N.B.: This is expected to be the last release with TrueType fonts built by default; OpenType versions will replace the legacy TrueType fonts in future releases. It will still be possible to manually build the TrueType fonts in the future with the "make truetype" command in the font directory. That make command is already implemented and so is available for experimentation.**
- Minseo Lee (이민서) made further modifications to the glyphs used to generate the Hangul Syllables block (U+AC00..U+D7A3), and modified Hangul glyphs in the ranges U+3131.U+318E, U+3200..U+321E, and U+3260..U+327F to match the style of the new Hangul Syllables glyphs.

## 3 June 2023 (Unifont 15.0.05)
- Minseo Lee (이민서) has contributed a new Hangul Syllables block of 11,172 glyphs generated by the Unifont package's johab2ucs2 script, which he altered slightly. Details are in the ChangeLog file.

## 28 May 2023 (Unifont 15.0.04)
- This release is a minor update with some redrawn Greek and Coptic letters (U+0370..U+03FF): tonos moved down and to the left of capital vowels, baselines and x-heights adjusted for consistency, etc. Two redrawn heart icons. Glyphs for the CSUR script Engsvanyáli have also been added. Full details are in the ChangeLog file.

utils/buildactions/install_unifont.lua

@@ -4,13 +4,13 @@ premake.modules.install_unifont = {}
 
 -- Config variables
 local UNIFONT_BASEURL = "https://github.com/multitheftauto/unifont/releases/download/"
-local UNIFONT_DOWNLOAD_FILENAME = "unifont-15.0.03.ttf"
+local UNIFONT_DOWNLOAD_FILENAME = "unifont-15.0.06.ttf"
 local UNIFONT_FILENAME = "unifont.ttf"
 local UNIFONT_PATH = "Shared/data/MTA San Andreas/MTA/cgui"
 
 -- Change these to update the version
-local UNIFONT_TAG = "v15.0.03"
-local UNIFONT_HASH = "ca921647a9a34e1e85a541b74cbfc780389d4c3b6bac9f5fbedb9e771b1597bd"
+local UNIFONT_TAG = "v15.0.06"
+local UNIFONT_HASH = "9282b6eff54eeca2e7f58c9a40a91049bd219f3e6a45fbee8eba013379b9af3a"
 
 newaction {
 	trigger = "install_unifont",