fix build error for python bindings on some systems (chapel-lang#26330)

This fixes the generated rpath string for the python bindings shared
library. There is a typo in the current version that creates separation
and omits a comma from the linker flags format. This can cause a build
error when installing Chapel in a prefix on some systems, like
perlmutter.

[reviewed by @jabraham17 - thanks!]

tools/chapel-py/setup.py

@@ -64,9 +64,8 @@
 LDFLAGS = []
 LDFLAGS += [
     "-L{}".format(chpl_lib_path),
+    "-Wl,-rpath,{}".format(chpl_lib_path),
     "-lChplFrontendShared",
-    "-Wl,-rpath",
-    chpl_lib_path,
 ]
 
 if str(chpl_variables.get("CHPL_SANITIZE")) == "address":