src/bin/sage-env: Update MACOSX_DEPLOYMENT_TARGET in builds with python3 from SPKG

[mkoeppe]

(from #30494)

Previous tickets: #27824, #18272, #16312

Depends on #30724

CC: @jhpalmieri

Component: porting

Issue created by migration from https://trac.sagemath.org/ticket/30711

[mkoeppe]

Description changed:

--- 
+++ 
@@ -1,3 +1,4 @@
 (from #30494)
 
+Previous tickets: #27824, #18272, #16312
 

[mkoeppe]

Dependencies: #30724

[mkoeppe]

comment:2

Depends on #30724 - which touches the same code

[jhpalmieri]

comment:4

There is a branch at #18272 that may handle this issue.

[mkoeppe]

comment:5

Sage development has entered the release candidate phase for 9.3. Setting a new milestone for this ticket based on a cursory review.

[mkoeppe]

comment:6

The code that was setting MACOSX_DEPLOYMENT_TARGET was removed in #18272, so we can close this ticket.

[jhpalmieri]

comment:7

I agree.