git 2.44.0: gitk doesn't run, "no display name and no $DISPLAY environment variable"

[gwerbin (Greg Werbin)]

I get the following error when I run /opt/local/bin/gitk on MacOS 12.7 (M1 ARM):

% /opt/local/bin/gitk

application-specific initialization failed: no display name and no $DISPLAY environment variable
Error in startup script: no display name and no $DISPLAY environment variable
    while executing
"load /opt/local/lib/libtk8.6.dylib"
    ("package ifneeded Tk 8.6.14" script)
    invoked from within
"package require Tk"
    (file "/opt/local/bin/gitk" line 10)

Not sure if this is related to ​https://trac.macports.org/ticket/62988.