fix capitalization in test (#139643)

Author: klausler

flang/test/Semantics/PowerPC/ppc-vector-types04.f90

@@ -4,7 +4,7 @@
 subroutine vec_type_test(arg1, arg2, arg3, arg4)
 !ERROR: Assumed-shape entity of vector(real(4)) type is not supported
   vector(real) :: arg1(:)
-!ERROR: Assumed Rank entity of vector(unsigned(4)) type is not supported
+!ERROR: Assumed rank entity of vector(unsigned(4)) type is not supported
   vector(unsigned) :: arg2(..)
 !ERROR: Deferred-shape entity of vector(integer(4)) type is not supported
   vector(integer), allocatable :: arg3(:)
@@ -19,7 +19,7 @@ end subroutine vec_type_test
 subroutine vec_pair_type_test(arg1, arg2, arg3, arg4)
 !ERROR: Assumed-shape entity of __vector_pair type is not supported
   __vector_pair :: arg1(:)
-!ERROR: Assumed Rank entity of __vector_pair type is not supported
+!ERROR: Assumed rank entity of __vector_pair type is not supported
   __vector_pair :: arg2(..)
 !ERROR: Deferred-shape entity of __vector_pair type is not supported
   __vector_pair, allocatable :: arg3(:)
@@ -34,7 +34,7 @@ end subroutine vec_pair_type_test
 subroutine vec_quad_type_test(arg1, arg2, arg3, arg4)
 !ERROR: Assumed-shape entity of __vector_quad type is not supported
   __vector_quad :: arg1(:)
-!ERROR: Assumed Rank entity of __vector_quad type is not supported
+!ERROR: Assumed rank entity of __vector_quad type is not supported
   __vector_quad :: arg2(..)
 !ERROR: Deferred-shape entity of __vector_quad type is not supported
   __vector_quad, allocatable :: arg3(:)