Bump golang from 1.20.7 to 1.21.1 (#234)

* Bump golang from 1.20.7 to 1.21.1

Bumps golang from 1.20.7 to 1.21.1.

---
updated-dependencies:
- dependency-name: golang
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

* bump golang version in go mod

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Tobias Lindberg <tobias.ehlert@gmail.com>

Dockerfile

@@ -1,5 +1,5 @@
 # get golang container
-FROM golang:1.20.7
+FROM golang:1.21.1
 
 # get args
 ARG apiVersion=unknown

go.mod

@@ -1,6 +1,6 @@
 module github.com/tobiasehlert/teslamateapi
 
-go 1.20
+go 1.21
 
 require (
 	github.com/eclipse/paho.mqtt.golang v1.4.3