PipeWire camera: drop redundant <pipewire/core.h> include

We already include main <pipewire/pipewire.h> header, which includes all
the PipeWire headers, making <pipewire/core.h> to be included twice.

This breaks Firefox builds, where using system libraries we have to list
all system headers, making Firefox to unnecessarily list "core.h" header
in the list, while "pipewire.h" should be enough.

Bug: webrtc:42225999
Change-Id: Icc8153583a976aa9b3bd7138f932a0642d93a55e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/381700
Commit-Queue: Jan Grulich <grulja@gmail.com>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#44162}

modules/video_capture/linux/pipewire_session.h

diff --git a/modules/video_capture/linux/pipewire_session.h b/modules/video_capture/linux/pipewire_session.h
index 84273ea..5420a7f 100644
--- a/modules/video_capture/linux/pipewire_session.h
+++ b/modules/video_capture/linux/pipewire_session.h
@@ -11,7 +11,6 @@
 #ifndef MODULES_VIDEO_CAPTURE_LINUX_PIPEWIRE_SESSION_H_
 #define MODULES_VIDEO_CAPTURE_LINUX_PIPEWIRE_SESSION_H_
 
-#include <pipewire/core.h>
 #include <pipewire/pipewire.h>
 
 #include <deque>