[release] add 1.60 to interop matrix (#35274)

Closes #35274

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/35274 from markdroth:release_interop_matrix_update b1cfcad14b
PiperOrigin-RevId: 590257600

tools/interop_matrix/client_matrix.py

@@ -129,6 +129,7 @@ LANG_RELEASE_MATRIX = {
             ("v1.56.0", ReleaseInfo()),
             ("v1.57.0", ReleaseInfo()),
             ("v1.58.0", ReleaseInfo()),
+            ("v1.60.0", ReleaseInfo()),
         ]
     ),
     "go": OrderedDict(
@@ -753,6 +754,12 @@ LANG_RELEASE_MATRIX = {
                     runtimes=["python"], testcases_file="python__master"
                 ),
             ),
+            (
+                "v1.60.0",
+                ReleaseInfo(
+                    runtimes=["python"], testcases_file="python__master"
+                ),
+            ),
         ]
     ),
     "node": OrderedDict(
@@ -846,6 +853,7 @@ LANG_RELEASE_MATRIX = {
             ("v1.56.0", ReleaseInfo()),
             ("v1.57.0", ReleaseInfo()),
             ("v1.58.0", ReleaseInfo()),
+            ("v1.60.0", ReleaseInfo()),
         ]
     ),
     "php": OrderedDict(
@@ -903,6 +911,7 @@ LANG_RELEASE_MATRIX = {
             ("v1.56.0", ReleaseInfo()),
             ("v1.57.0", ReleaseInfo()),
             ("v1.58.0", ReleaseInfo()),
+            ("v1.60.0", ReleaseInfo()),
         ]
     ),
     "csharp": OrderedDict(