Fix git hooks

.lefthook/pre-commit/lint

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-if ! git diff --name-only | grep -qe ".*\.go$"; then
+if ! git diff --staged --name-only | grep -qe ".*\.go$"; then
   echo "Nothing to lint"
   exit 0;
 fi

.lefthook/pre-push/test

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-if ! git diff --name-only | grep -qe ".*\.(go|h|c)$"; then
+if ! git diff --staged --name-only | grep -qe ".*\.(go|h|c)$"; then
   echo "Nothing to test"
   exit 0;
 fi