[tepl] Bump API/major version to 6

[Sébastien Wilmet <swilmet src gnome org>]

commit 812525c6aaa2a78f2a6f07b5ff7ba86f1d95b756
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Nov 9 22:51:59 2020 +0100

    Bump API/major version to 6
    
    Because there has been an API break.

 README.md   | 2 +-
 meson.build | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/README.md b/README.md
index 9e14d3a..9ed98b2 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 Tepl - Text editor product line
 ===============================
 
-This is version 5.1.2 of Tepl.
+This is version 5.99.0 of Tepl.
 
 Tepl is a library that eases the development of GtkSourceView-based text
 editors and IDEs.
diff --git a/meson.build b/meson.build
index 5ecbdf9..10af742 100644
--- a/meson.build
+++ b/meson.build
@@ -6,7 +6,7 @@
 project(
   'tepl', 'c',
   meson_version: '>= 0.53',
-  version: '5.1.2',
+  version: '5.99.0',
   default_options: ['warning_level=2']
 )
 
@@ -39,7 +39,7 @@ lt_age = 0
 TEPL_LT_VERSION = '@0@.@1@.@2@'.format(lt_current, lt_revision, lt_age)
 
 # API version, used for parallel installability.
-TEPL_API_VERSION = '5'
+TEPL_API_VERSION = '6'
 
 TEPL_PUBLIC_DEPS = [
   dependency('gio-2.0', version: '>= 2.64'),