patch 8.2.0183: tests fail when the float feature is disabled

Problem:    Tests fail when the float feature is disabled.
Solution:   Skip tests that don't work without float support.
diff --git a/src/testdir/test_partial.vim b/src/testdir/test_partial.vim
index e7a7d05..3cd0be2 100644
--- a/src/testdir/test_partial.vim
+++ b/src/testdir/test_partial.vim
@@ -106,7 +106,7 @@
 endfu
 
 fun OuterCall()
-  let opt = { 'func' : function('sin') }
+  let opt = { 'func' : function('max') }
   call InnerCall(opt.func)
 endfu