chore(deps): update dependency numpy to v1.18.4 [(#3675)](GoogleCloudPlatform/python-docs-samples#3675)

Co-authored-by: Bu Sun Kim <[email protected]>
Co-authored-by: Takashi Matsuo <[email protected]>

Author: 3 people

samples/snippets/classify_text/requirements.txt

@@ -1,2 +1,2 @@
 google-cloud-language==1.3.0
-numpy==1.18.3
+numpy==1.18.4