bumped version to 0.5.4
bumped version to 0.5.4

lilulu/openmc,wbinventor/openmc,amandalund/openmc,lilulu/openmc,wbinventor/openmc,smharper/openmc,mjlong/openmc,shikhar413/openmc,paulromano/openmc,amandalund/openmc,walshjon/openmc,bhermanmit/openmc,liangjg/openmc,samuelshaner/openmc,nhorelik/openmc,samuelshaner/openmc,walshjon/openmc,bhermanmit/openmc,liangjg/openmc,sxds/opemmc,paulromano/openmc,walshjon/openmc,kellyrowland/openmc,johnnyliu27/openmc,shikhar413/openmc,amandalund/openmc,nhorelik/openmc,johnnyliu27/openmc,smharper/openmc,shikhar413/openmc,liangjg/openmc,mit-crpg/openmc,smharper/openmc,mit-crpg/openmc,shenqicang/openmc,mit-crpg/openmc,sxds/opemmc,samuelshaner/openmc,amandalund/openmc,paulromano/openmc,mjlong/openmc,walshjon/openmc,samuelshaner/openmc,wbinventor/openmc,liangjg/openmc,johnnyliu27/openmc,shikhar413/openmc,lilulu/openmc,smharper/openmc,wbinventor/openmc,paulromano/openmc,kellyrowland/openmc,shenqicang/openmc,johnnyliu27/openmc,mit-crpg/openmc