[pitivi] build: Fix build when python-embeded is not found

[Thibault Saunier <tsaunier src gnome org>]

commit 9fc400ca6f3f59fd2b2abfb8e39f0cf7a4031e09
Author: Thibault Saunier <tsaunier igalia com>
Date:   Thu Jan 30 12:34:41 2020 -0300

    build: Fix build when python-embeded is not found
    
    Error message is:
    
    ```
        meson.build:11:2: ERROR: Function does not take positional arguments.
    ```

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 060ab47a..e7d7aa73 100644
--- a/meson.build
+++ b/meson.build
@@ -8,7 +8,7 @@ pythonver = python.language_version()
 # https://gitlab.freedesktop.org/gstreamer/gst-python/issues/28
 python_dep = dependency('python-@0@-embed'.format(pythonver), version: '>= 3.3', required: false)
 if not python_dep.found()
-  python_dep = python.dependency('python3', version: '>= 3.3')
+  python_dep = python.dependency(version: '>= 3.3')
 endif
 
 if get_option('build-gst')