build: use Go 1.27, minimum version is Go 1.26 (#10864)

### Purpose

🎉

Signed-off-by: Jakob Borg <jakob@kastelo.net>

.github/workflows/build-infra-dockers.yaml

@@ -7,7 +7,7 @@ on:
       - infra-*
 
 env:
-  GO_VERSION: "~1.26.0"
+  GO_VERSION: "~1.27.0"
   CGO_ENABLED: "0"
   BUILD_USER: docker
   BUILD_HOST: github.syncthing.net

.github/workflows/build-syncthing.yaml

@@ -18,7 +18,7 @@ env:
   # The go version to use for builds. We set check-latest to true when
   # installing, so we get the latest patch version that matches the
   # expression.
-  GO_VERSION: "~1.26.0"
+  GO_VERSION: "~1.27.0"
 
   # Optimize compatibility on the slow architectures.
   GOMIPS: softfloat
@@ -108,7 +108,7 @@ jobs:
         runner: ["windows-latest", "ubuntu-latest", "macos-latest"]
         # The oldest version in this list should match what we have in our go.mod.
         # Variables don't seem to be supported here, or we could have done something nice.
-        go: ["~1.25.0", "~1.26.0"]
+        go: ["~1.26.0", "~1.27.0"]
     runs-on: ${{ matrix.runner }}
     steps:
       - name: Set git to use LF