Change version to follow scheme used by GNOME

Cargo.lock

@@ -1003,7 +1003,7 @@ dependencies = [
 
 [[package]]
 name = "fractal"
-version = "0.0.1"
+version = "5.0.0-alpha"
 dependencies = [
  "ashpd",
  "async-stream",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fractal"
-version = "0.0.1"
+version = "5.0.0-alpha"
 authors = ["Julian Sparber <julian@sparber.net>"]
 edition = "2018"
 

meson.build

@@ -1,6 +1,6 @@
 project('fractal',
         'rust',
-        version: '0.0.1',
+        version: '5.alpha',
         license: 'GPL-3.0-or-later',
         meson_version: '>= 0.59')
 
@@ -36,10 +36,6 @@ appstream_util = find_program('appstream-util', required: false)
 cargo = find_program('cargo', required: true)
 
 version = meson.project_version()
-version_array = version.split('.')
-major_version = version_array[0].to_int()
-minor_version = version_array[1].to_int()
-version_micro = version_array[2].to_int()
 
 prefix = get_option('prefix')
 bindir = prefix / get_option('bindir')