update nccl cmake version

cmake/external_libs/nccl.cmake

@@ -1,14 +1,14 @@
 if (ENABLE_GITEE)
-    set(REQ_URL "https://gitee.com/mirrors/nccl/repository/archive/v2.4.8-1.tar.gz")
-    set(MD5 "e3078a91635f6ac12927e9fa5a7248ec")
+    set(REQ_URL "https://gitee.com/mirrors/nccl/repository/archive/v2.7.6-1.tar.gz")
+    set(MD5 "220d232b30cb9bff2e54219399b9f6fb")
 else()
-    set(REQ_URL "https://github.com/NVIDIA/nccl/archive/v2.4.8-1.tar.gz")
-    set(MD5 "f14b37d6af1c79db5f57cb029a753727")
+    set(REQ_URL "https://github.com/NVIDIA/nccl/archive/v2.7.6-1.tar.gz")
+    set(MD5 "073b19899f374c5ba07d2db02dc38f9f")
 endif ()
 
 set(nccl_CFLAGS "-D_FORTIFY_SOURCE=2 -O2")
 mindspore_add_pkg(nccl
-        VER 2.4.8-1
+        VER 2.7.6-1
         LIBS nccl
         URL ${REQ_URL}
         MD5 ${MD5}