build: Fix build when python-embeded is not found

Error message is:

```
    meson.build:11:2: ERROR: Function does not take positional arguments.
```
4 jobs for master in 84 minutes and 53 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Docker Image
passed #580745
pitivi:1.0

01:10:22

passed #580744
pitivi:master

01:12:51

 
  Build
passed #580746
build

00:11:50

 
  Deploy
passed #580747
PitiviBuildMachine
deploy

00:00:12