cirrus: update ref to Tcl version for OSX test

Author: xdelaruelle

.cirrus.yml

@@ -100,7 +100,7 @@ task:
     # keep Tcl 8 as current Nagelfar archive requires 8.5+, but not Tcl 9
     - brew install md5sha1sum expect dejagnu grep fish r tcl-tk@8 gzip powershell
   configure_script:
-    - ./configure --prefix=/tmp/modules --with-loadedmodules=null:dot --with-tcl=/opt/homebrew/Cellar/tcl-tk@8/8.6.15/lib
+    - ./configure --prefix=/tmp/modules --with-loadedmodules=null:dot --with-tcl=/opt/homebrew/Cellar/tcl-tk@8/8.6.16/lib
   << : *BUILD_INSTALL_TEST_TEMPLATE
   coverage_script:
     - for f in tcl/*.tcl; do script/nglfar2ccov $f; done