patch 9.1.1065: no digraph for "Approaches the limit"

Problem:  no digraph for "Approaches the limit"
Solution: Add the digraph using .= (Hans Ginzel)

Add digraph Approaches the Limit

≐ U+2250 https://www.fileformat.info/info/unicode/char/2250/index.htm

closes: #16508

Signed-off-by: Hans Ginzel <hans@matfyz.cz>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/digraph.c b/src/digraph.c
index 32b36be..a5dff00 100644
--- a/src/digraph.c
+++ b/src/digraph.c
@@ -997,6 +997,7 @@
 	{'?', '=', 0x2245},
 	{'?', '2', 0x2248},
 	{'=', '?', 0x224c},
+	{'.', '=', 0x2250},
 	{'H', 'I', 0x2253},
 	{'!', '=', 0x2260},
 	{'=', '3', 0x2261},