Check required Stata version

[jorpppp]

Most of our programs have version 11.2 statements. Check if this is correct and update version statements accordingly.

[jorpppp]

We do require version 6.x of reghdfe when using reghdfe. From https://github.com/sergiocorreia/ivreghdfe/blob/cc35a985032931750036c5762cc88415f2f1c04c/src/ivreghdfe.ado#L52 reghdfe 6.x requires version 13, so it may make sense to update our version statements to version 13.

[jorpppp]

Note that eventstudyinteract from where we get our Sun and Abraham code also requires Stata 13: https://github.com/lsun20/EventStudyInteract/blob/87d16affd23f8bea20cb312c9e02fea0f1d87fe5/eventstudyinteract.ado#L4

[jorpppp]

Among other packages for diff in diff and event studies:

• csdid requires Stata 14
• did_imputation requires Stata 13: https://github.com/borusyak/did_imputation/blob/767c8d6670a751170910d419bbafd323df92ef08/did_imputation.ado#L7
• did_multiplegt requires Stata 12
• did_2s requires Stata 13
• eventdd requirse Stata 13: https://github.com/damiancclarke/eventdd/blob/5b499f662acdfca8ce0399cf82c0222be2072223/eventdd.ado#L7
• eventstudyinteract requires Stata 13, see above
• jwdid requires Stata 15
• lpdid requires Stata 13
• staggered requires Stata 14.1: https://github.com/mcaceresb/stata-staggered/blob/320c4df86cf4461c51c5f922132404759445f600/src/ado/staggered.ado#L5
• wooldid requires Stata 16: https://github.com/thegland/wooldid/blob/7f3b814ebb2917fc61a527040905fa98e51d13b1/wooldidinstall/wooldid.ado#L13

[jorpppp]

From the above I will update the version statements to version 13

[jorpppp]

Summary: In this issue we changed version statements from 11.2 to 13, to be consistent with the version required in package dependencies.