fix(deps): google-gax v2.17.0 with mTLS (#907)

Author: Benjamin E. Coe

handwritten/bigtable/package.json

@@ -53,7 +53,7 @@
     "dot-prop": "^6.0.0",
     "escape-string-regexp": "^4.0.0",
     "extend": "^3.0.2",
-    "google-gax": "^2.12.0",
+    "google-gax": "^2.17.0",
     "is": "^3.0.1",
     "is-utf8": "^0.2.1",
     "lodash.snakecase": "^4.1.1",