Update git submodules

* Update org.eclipse.mylyn from branch 'master'
  to 926f6c56fa67543e662acf1afd6dac084e75e006
  - 545757: Fix failing Mylyn Docs builds
    
    * Findbugs version issue was causing Mylyn builds to fail and most were
    fixed in this change https://git.eclipse.org/r/#/c/139447/
    
    * Wikitext build was still having the findbugs issue though, so I think
    it's using the version information from maven-parent instead of
    mylyn-parent.  So I'm updating the version to match what fixed the
    problem in the other builds.
    
    Change-Id: I888bbf590c36120499f9b18ba885c91e239fb7bc
    Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=545757
    Signed-off-by: Dawn Baikie <dawn.baikie@tasktop.com>
1 file changed