[ticket/13045] Remove Pragma headers

PHPBB3-13045
Merge pull request #2963 from Senky/ticket/13045

[ticket/13045] Remove Pragma headers
Merge branch 'develop-ascraeus' into develop

# By Jakub Senko
# Via Dhruv Goel (1) and Jakub Senko (1)
* develop-ascraeus:
  [ticket/13045] Remove Pragma headers