chore: fixup 1.17 -> 1.18 things

internal/gapicgen/cmd/genbot/Dockerfile

@@ -16,7 +16,7 @@ RUN apk add protoc protobuf-dev
 RUN protoc --version
 
 # Install Go.
-RUN wget -O /tmp/go.tgz https://dl.google.com/go/go1.17.linux-amd64.tar.gz && \
+RUN wget -O /tmp/go.tgz https://dl.google.com/go/go1.18.linux-amd64.tar.gz && \
     tar -C /usr/local -xzf /tmp/go.tgz && \
     rm /tmp/go.tgz
 ENV PATH /usr/local/go/bin:$PATH

internal/gapicgen/go.mod

@@ -1,6 +1,6 @@
 module cloud.google.com/go/internal/gapicgen
 
-go 1.17
+go 1.18
 
 require (
 	cloud.google.com/go v0.100.2

internal/kokoro/check_incompat_changes.sh

@@ -17,7 +17,7 @@
 set -x
 
 # Only run apidiff checks on latest (we only need it once).
-if [[ `go version` != *"go1.17"* ]]; then
+if [[ `go version` != *"go1.18"* ]]; then
     exit 0
 fi
 

internal/kokoro/vet.sh

@@ -19,7 +19,7 @@ set -e
 # Display commands being run
 set -x
 
-if [[ $(go version) != *"go1.17"* ]]; then
+if [[ $(go version) != *"go1.18"* ]]; then
   exit 0
 fi