chore(deps): update dependency gcp-releasetool to v2 (#49)

Co-authored-by: Averi Kitsch <akitsch@google.com>

Author: renovate-bot

.kokoro/requirements.txt

@@ -149,9 +149,9 @@ gcp-docuploader==0.6.5 \
     --hash=sha256:30221d4ac3e5a2b9c69aa52fdbef68cc3f27d0e6d0d90e220fc024584b8d2318 \
     --hash=sha256:b7458ef93f605b9d46a4bf3a8dc1755dad1f31d030c8679edf304e343b347eea
     # via -r requirements.in
-gcp-releasetool==1.17.0 \
-    --hash=sha256:1a759f4b0906f4ea9dc7db3649aa11a632c72f6dc6a54f10cf57c1925d034a1c \
-    --hash=sha256:f23db51d85484998af5549181be726f177bf90b481de238fe7a99ec970266b6b
+gcp-releasetool==2.0.0 \
+    --hash=sha256:3d73480b50ba243f22d7c7ec08b115a30e1c7817c4899781840c26f9c55b8277 \
+    --hash=sha256:7aa9fd935ec61e581eb8458ad00823786d91756c25e492f372b2b30962f3c28f
     # via -r requirements.in
 google-api-core==2.17.1 \
     --hash=sha256:610c5b90092c360736baccf17bd3efbcb30dd380e7a6dc28a71059edb8bd0d8e \