patch 8.2.1707: small inconsitency in highlight test

Problem:    Small inconsitency in highlight test.
Solution:   Use one argument for :execute. (Antony Scriven, #6975)
diff --git a/src/testdir/test_highlight.vim b/src/testdir/test_highlight.vim
index a1c80cd..05f215a 100644
--- a/src/testdir/test_highlight.vim
+++ b/src/testdir/test_highlight.vim
@@ -886,11 +886,11 @@
   let patContextDefault = fnamemodify(scriptContextDefault, ':t') .. ' line 1'
   let patContextRelink = fnamemodify(scriptContextRelink, ':t') .. ' line 2'
 
-  exec "source" scriptContextDefault
+  exec 'source ' .. scriptContextDefault
   let hlContextDefault = execute("verbose hi Context")
   call assert_match(patContextDefault, hlContextDefault)
 
-  exec "source" scriptContextRelink
+  exec 'source ' .. scriptContextRelink
   let hlContextRelink = execute("verbose hi Context")
   call assert_match(patContextRelink, hlContextRelink)
 
diff --git a/src/version.c b/src/version.c
index 93f7701..fd880f5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1707,
+/**/
     1706,
 /**/
     1705,