update Bob, buildkit-golang (bump Go, get Genny)

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
         buildx-version: v0.4.1
         qemu-version: latest
     - name: Download Turbo Bob
-      run: curl --fail --location --output bob https://dl.bintray.com/function61/dl/turbobob/20200617_1743_510a0529/bob_linux-amd64 && chmod +x bob
+      run: curl --fail --location --output bob https://github.com/function61/turbobob/releases/download/20200910_1241_90ec91c9/bob_linux-amd64 && chmod +x bob
     - name: Build with Turbo Bob
       run: CI_REVISION_ID="$GITHUB_SHA" ./bob build --publish-artefacts
       # unfortunately there doesn't seem to be a way to "expose all secrets", so you must

turbobob.json

@@ -5,13 +5,16 @@
 	"builders": [
 		{
 			"name": "default",
-			"uses": "docker://fn61/buildkit-golang:20200612_1221_eca6dcb6",
+			"uses": "docker://fn61/buildkit-golang:20200910_1302_9f256d7b",
 			"mount_destination": "/workspace",
 			"workdir": "/workspace",
 			"commands": {
 				"build": ["bin/build.sh"],
 				"dev": ["bash"]
-			}
+			},
+			"dev_shell_commands": [
+				{ "command": "rel/horizon_linux-amd64", "important": false }
+			]
 		},
 		{
 			"name": "publisher",