Bump go version to 1.20 (#1285)

Author: waciumawanjohi

.github/workflows/release.yaml

@@ -30,7 +30,7 @@ jobs:
       - name: set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: '^1.19.9'
+          go-version-file: 'go.mod'
 
       - name: setup carvel tooling binaries
         uses: vmware-tanzu/carvel-setup-action@v1

.github/workflows/validation.yaml

@@ -37,7 +37,7 @@ jobs:
       - name: set up Go
         uses: actions/setup-go@v4
         with:
-          go-version: '^1.19.9'
+          go-version-file: 'go.mod'
 
       - name: setup carvel tooling binaries
         uses: vmware-tanzu/carvel-setup-action@v1

go.mod

@@ -1,6 +1,6 @@
 module github.com/vmware-tanzu/cartographer
 
-go 1.19
+go 1.20
 
 require (
 	github.com/MakeNowJust/heredoc v1.0.0