deps: update dependency pyjwt to v2.8.0 (#2172)

Author: renovate-bot

.kokoro/requirements.txt

@@ -357,9 +357,9 @@ pycparser==2.21 \
     --hash=sha256:8ee45429555515e1f6b185e78100aea234072576aa43ab53aefcae078162fca9 \
     --hash=sha256:e644fdec12f7872f86c58ff790da456218b10f863970249516d60a5eaca77206
     # via cffi
-pyjwt==2.4.0 \
-    --hash=sha256:72d1d253f32dbd4f5c88eaf1fdc62f3a19f676ccbadb9dbc5d07e951b2b26daf \
-    --hash=sha256:d42908208c699b3b973cbeb01a969ba6a96c821eefb1c5bfe4c390c01d67abba
+PyJWT==2.8.0 \
+    --hash=sha256:57e28d156e3d5c10088e0c68abb90bfac3df82b40a71bd0daa20c65ccd5c23de \
+    --hash=sha256:59127c392cc44c2da5bb3192169a91f429924e17aff6534d70fdc02ab3e04320
     # via gcp-releasetool
 pyparsing==3.0.9 \
     --hash=sha256:2b020ecf7d21b687f219b71ecad3631f644a47f01403fa1d1036b0c6416d70fb \