ci: Upgrade to Go 1.15 (#3642)

* ci: Try Go 1.15 RC1 out of curiosity

* Go 1.15 was released; let's try it

* Update to latest quic-go

* Attempt at fixing broken test

Co-authored-by: Matthew Holt <mholt@users.noreply.github.com>

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest, macos-latest, windows-latest ]
-        go-version: [ 1.14.x ]
+        go-version: [ 1.14.x, 1.15.x ]
 
         # Set some variables per OS, usable via ${{ matrix.VAR }}
         # CADDY_BIN_PATH: the path to the compiled Caddy binary, for artifact publishing
@@ -39,7 +39,7 @@ jobs:
 
     steps:
     - name: Install Go
-      uses: actions/setup-go@v1
+      uses: actions/setup-go@v2
       with:
         go-version: ${{ matrix.go-version }}
 

.github/workflows/cross-build.yml

@@ -14,7 +14,7 @@ jobs:
       fail-fast: false
       matrix:
         goos: ['android', 'linux', 'solaris', 'illumos', 'dragonfly', 'freebsd', 'openbsd', 'plan9', 'windows', 'darwin', 'netbsd']
-        go-version: [ 1.14.x ]
+        go-version: [ 1.14.x, 1.15.x ]
     runs-on: ubuntu-latest
     continue-on-error: true
     steps: