Fix incorrect PKG_BRANCH (#39257)

staticfloat · web-flow · commit 367841a05425 · 2021-01-14T21:08:14.000+01:00
diff --git a/stdlib/Pkg.version b/stdlib/Pkg.version
@@ -1,2 +1,2 @@
-PKG_BRANCH = release-1.6
+PKG_BRANCH = master
 PKG_SHA1 = 9b78818f09ea7e938bbb514f2056c6241714716f
