Bump go from 1.19 to 1.20 (#3080)

* Bump go from 1.19 to 1.20

The current stable version on https://go.dev/dl/ is 1.21 and we support the last two minor versions. This unblocks part of #3079.

* Fix setup-go checking out go1.2 instead of 1.20

.github/workflows/test.yaml

@@ -21,7 +21,9 @@ jobs:
 
     - uses: actions/setup-go@93397bea11091df50f3d7e59dc26a7711a8bcfbe # v4.1.0
       with:
-        go-version: 1.19
+        go-version: '1.20'
+        check-latest: true
+        cache: true
 
     - uses: golangci/golangci-lint-action@3a919529898de77ec3da873e3063ca4b10e7f5cc # v3.7.0
       with:
@@ -35,7 +37,7 @@ jobs:
 
     - uses: actions/setup-go@93397bea11091df50f3d7e59dc26a7711a8bcfbe # v4.1.0
       with:
-        go-version: '1.19'
+        go-version: '1.20'
         check-latest: true
         cache: true
 
@@ -49,7 +51,7 @@ jobs:
 
     - uses: actions/setup-go@93397bea11091df50f3d7e59dc26a7711a8bcfbe # v4.1.0
       with:
-        go-version: '1.19'
+        go-version: '1.20'
         check-latest: true
         cache: true
 

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## HEAD
 
+* Recommended go version for development: 1.20
+  * This is the version used by the cloudbuild presubmits. Using a
+    different version can lead to presubmits failing due to unexpected
+    diffs.
+
+
 ## v.1.5.2
 
 * Recommended go version for development: 1.19

README.md

@@ -73,7 +73,7 @@ The current state of feature implementation is recorded in the
 
 To build and test Trillian you need:
 
- - Go 1.19 or later (go 1.19 matches cloudbuild, and is preferred for developers
+ - Go 1.20 or later (go 1.20 matches cloudbuild, and is preferred for developers
    that will be submitting PRs to this project).
 
 To run many of the tests (and production deployment) you need:

go.mod

@@ -1,6 +1,6 @@
 module github.com/google/trillian
 
-go 1.19
+go 1.20
 
 require (
 	bitbucket.org/creachadair/shell v0.0.7