ci: install gosimports (#25400)

https://github.com/hashicorp/vault/pull/25383 add gosimports to the list
of external tools that are required. The precheck for some linting
workflows fail because we didn't add a corresponding workflow to install
them.

Signed-off-by: Ryan Cragun <me@ryan.ec>

tools/tools.sh

@@ -40,13 +40,13 @@ install_external() {
     github.com/favadi/protoc-go-inject-tag@latest
     github.com/golangci/misspell/cmd/misspell@latest
     github.com/golangci/revgrep/cmd/revgrep@latest
+    github.com/rinchsan/gosimports/cmd/gosimports@latest
     golang.org/x/tools/cmd/goimports@latest
     google.golang.org/protobuf/cmd/protoc-gen-go@latest
     google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
     gotest.tools/gotestsum@latest
     honnef.co/go/tools/cmd/staticcheck@latest
     mvdan.cc/gofumpt@latest
-    github.com/rinchsan/gosimports/cmd/gosimports@latest
   )
 
   echo "==> Installing external tools..."
@@ -66,6 +66,7 @@ check_external() {
     buf
     gofumpt
     goimports
+    gosimports
     gotestsum
     misspell
     protoc-gen-go
@@ -73,7 +74,6 @@ check_external() {
     protoc-go-inject-tag
     revgrep
     staticcheck
-    gosimports
   )
 
   echo "==> Checking for external tools..."