.github/workflows: update to go 1.20 from 1.20rc1

And use go1.20 as the default go version.

Change-Id: I4c629f89911ab031a3228516befbbe4fbb98a281
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/470197
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Suzy Mueller <[email protected]>

Author: hyangah

.github/workflows/release-nightly.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v3
         with:
-         go-version: '1.19'
+         go-version: '1.20'
          check-latest: true
          cache: true
 

.github/workflows/test-long-all.yml

@@ -17,7 +17,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
         version: ['stable', 'insiders']
-        go: ['1.17', '1.18', '1.19', '1.20.0-rc.1']
+        go: ['1.17', '1.18', '1.19', '1.20']
 
     steps:
       - name: Clone repository

.github/workflows/test-long.yml

@@ -16,7 +16,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest] # TODO: reenable macos-latest
         version: ['stable']
-        go: ['1.17', '1.18', '1.19', '1.20.0-rc.1']
+        go: ['1.17', '1.18', '1.19', '1.20']
 
     steps:
       - name: Clone repository

.github/workflows/test-smoke.yml

@@ -30,7 +30,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v3
         with:
-         go-version: '1.19'
+         go-version: '1.20'
          check-latest: true
          cache: true
 

.github/workflows/wiki.yml

@@ -35,7 +35,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.19'
+          go-version: '1.20'
           check-latest: true
           cache: true
           cache-dependency-path: '**/go.sum'