Release 1.38.0

Changes:
- 25 wide shapes have been added,
  so that every available layout now has a wide shape
- "PgUp" and "PgDn" on the terminal-layouts have been relabeled
  to "Page ↑" and "Page ↓"
- The Spanish and French terminal-layouts now have translated key-names
- The Spanish terminal-layout has been updated with the additional
keys that are already available on the US-terminal-layout.
- The wide and base shapes of the German layout had a different
  key-arrangement and the wide shape did not have a button to access
  additional characters; this has been fixed.

Development:
- Squeekboard's versioning now follows Phosh's versioning
  (for example: Squeekboard 1.38 was released in time for Phosh 0.38)
- The build-system has been simplified
  - A single Cargo.toml file is used,
    instead of assembling it from multiple parts
  - Newer dependencies are now used for building Squeekboard by default
- Squeekboard's main development-platform is now Debian Testing
- The layout-files have been cleaned up,
  so that those are easier to understand and edit

Part-of: <https://gitlab.gnome.org/World/Phosh/squeekboard/-/merge_requests/631>

meson.build

@@ -1,7 +1,7 @@
 project(
     'squeekboard',
     'c', 'rust',
-    version: '1.24.0',
+    version: '1.38.0',
     license: 'GPLv3',
     meson_version: '>=0.51.0',
     default_options: [