Change PRRTe submodule to point to head of v3.0 branch.

It formerly pointed to v2.1.

v3.0 is branched off of prrte/master around 7/26/2022.

Signed-off-by: Austen Lauria <awlauria@us.ibm.com>

Author: awlauria

.gitmodules

@@ -1,7 +1,7 @@
 [submodule "prrte"]
 	path = 3rd-party/prrte
 	url = ../../openpmix/prrte
-	branch = v2.1
+	branch = v3.0
 [submodule "openpmix"]
 	path = 3rd-party/openpmix
 	url = ../../openpmix/openpmix.git