Update git submodules

* Update plugins/plugin-manager from branch 'master'
  to 783f5c65c7dca522658efe10d57d1ac9ab5f9007
  - Add Gerrit logo to the intro page
    
    After 12 years of the Gerrit Code Review project
    add the logo to the splash page [1] displayed in the
    out of the box experience of Gerrit.
    
    By showing the diffy logo on the very first page
    the new users see when they first run Gerrit, the
    product gives the message of a renewed attention
    to the design and user-experience of modern
    Gerrit v3.
    
    [1] https://imgur.com/5gpumX8
    
    Change-Id: I6e7085759153c584350ce41e56328298f4f1954c
    
diff --git a/plugins/plugin-manager b/plugins/plugin-manager
index 9e7b0a0..783f5c6 160000
--- a/plugins/plugin-manager
+++ b/plugins/plugin-manager
@@ -1 +1 @@
-Subproject commit 9e7b0a086b3e4d56a3a9407d21b6648c650b8809
+Subproject commit 783f5c65c7dca522658efe10d57d1ac9ab5f9007