[3.7] bpo-34162: Fix idlelib/NEWS.text for 3.7.4 (#13067)

Author: terryjreedy

Lib/idlelib/NEWS.txt

@@ -1,5 +1,5 @@
-What's New in IDLE 3.7.3
-Released on 2019-??-??
+What's New in IDLE 3.7.4
+Released on 2019-06-24?
 ======================================
 
 
@@ -19,6 +19,11 @@ This param was only used twice and changed the return type.
 
 bpo-23216: IDLE: Add docstrings to search modules.
 
+
+What's New in IDLE 3.7.3
+Released on 2019-03-25
+======================================
+
 bpo-36176: Fix IDLE autocomplete & calltip popup colors.
 Prevent conflicts with Linux dark themes
 (and slightly darken calltip background).
@@ -74,7 +79,7 @@ Add some internal references within the IDLE doc.
 
 
 What's New in IDLE 3.7.2
-Released on 2018-12-21?
+Released on 2018-12-24
 ======================================
 
 bpo-34864: When starting IDLE on MacOS, warn if the system setting
@@ -117,7 +122,7 @@ The main change is the elimination of chapter-section numbers.
 
 
 What's New in IDLE 3.7.1
-Released on 2018-07-31?
+Released on 2018-10-20
 ======================================
 
 bpo-1529353: Output over N lines (50 by default) is squeezed down to a button.