[gnome-runtime-images] base: make sure python3-pip is installed

[Jordan Petridis <jpetridis src gnome org>]

commit ccc09ba35ba7f37ad632d60546cbd70c56903882
Author: Jordan Petridis <jordan centricular com>
Date:   Tue Oct 19 00:46:26 2021 +0300

    base: make sure python3-pip is installed
    
    It used to be there and got lost in the latest rebuild it seems.

 base | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/base b/base
index 9df219b..d1c7af1 100644
--- a/base
+++ b/base
@@ -20,7 +20,7 @@ WORKDIR /build
 RUN dnf upgrade -y --best --allowerasing && \
     dnf install -y flatpak flatpak-builder librsvg2 ostree fuse elfutils ccache \
     dconf dbus-daemon dbus-tools git bzr xorg-x11-server-Xvfb dbus-x11 python3-ruamel-yaml \
-    python3-gobject json-glib jq && \
+    python3-gobject python3-pip json-glib jq && \
     dnf clean all
 
 # generate machine-id as specified in the freedesktop spec: