build: upgrade from go 1.20.3 to 1.20.4 (#17056)

Includes CVE fixes that do *not* impact Nomad:

https://groups.google.com/g/golang-announce/c/MEb0UyuSMsU

.changelog/17056.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+build: Update from Go 1.20.3 to Go 1.20.4
+```

.circleci/config.yml

@@ -461,7 +461,7 @@ executors:
   go:
     working_directory: /go/src/github.com/hashicorp/nomad
     docker:
-      - image: docker.mirror.hashicorp.services/golang:1.20.3
+      - image: docker.mirror.hashicorp.services/golang:1.20.4
     resource_class: medium
     environment:
       <<: *common_envs
@@ -474,7 +474,7 @@ executors:
       resource_class: large
     environment: &machine_env
       <<: *common_envs
-      GOLANG_VERSION: 1.20.3
+      GOLANG_VERSION: 1.20.4
 
   go-macos:
     working_directory: ~/go/src/github.com/hashicorp/nomad
@@ -483,7 +483,7 @@ executors:
     environment:
       <<: *common_envs
       GOPATH: /Users/distiller/go
-      GOLANG_VERSION: 1.20.3
+      GOLANG_VERSION: 1.20.4
 
   go-windows:
     machine:
@@ -495,7 +495,7 @@ executors:
       GOPATH: c:\gopath
       GOBIN: c:\gopath\bin
       GOTESTSUM_PATH: c:\tmp\test-reports
-      GOLANG_VERSION: 1.20.3
+      GOLANG_VERSION: 1.20.4
       GOTESTSUM_VERSION: 1.7.0
       VAULT_VERSION: 1.4.1
 

.go-version

@@ -1 +1 @@
-1.20.3
+1.20.4

contributing/README.md

@@ -30,7 +30,7 @@ A development environment is supplied via Vagrant to make getting started easier
 
 Developing without Vagrant
 ---
-1. Install [Go 1.20.3+](https://golang.org/) *(Note: `gcc-go` is not supported)*
+1. Install [Go 1.20.4+](https://golang.org/) *(Note: `gcc-go` is not supported)*
 1. Clone this repo
    ```sh
    $ git clone https://github.com/hashicorp/nomad.git

scripts/release/mac-remote-build

@@ -56,7 +56,7 @@ REPO_PATH="${TMP_WORKSPACE}/gopath/src/github.com/hashicorp/nomad"
 mkdir -p "${TMP_WORKSPACE}/tmp"
 
 install_go() {
-  local go_version="1.20.3"
+  local go_version="1.20.4"
   local download=
 
   download="https://storage.googleapis.com/golang/go${go_version}.darwin-amd64.tar.gz"