ci: Update to Go 1.21 (#5719)

* ci: Update to Go 1.21

* Bump quic-go to v0.37.4

* Check EnableFullDuplex err

* Linter bug suppression

See https://github.com/timakin/bodyclose/issues/52

---------

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
           - windows-latest
         go: 
           - '1.20'
-          # - '1.21'
+          - '1.21'
 
         include:
         # Set the minimum Go patch version for the given Go minor
@@ -32,8 +32,8 @@ jobs:
         - go: '1.20'
           GO_SEMVER: '~1.20.6'
 
-        # - go: '1.21'
-        #   GO_SEMVER: '~1.21.0'
+        - go: '1.21'
+          GO_SEMVER: '~1.21.0'
 
         # Set some variables per OS, usable via ${{ matrix.VAR }}
         # CADDY_BIN_PATH: the path to the compiled Caddy binary, for artifact publishing