[buildbot] Bump buildbot version to latest stable release 3.8.0

[LEDE Commits]

ynezz pushed a commit to buildbot.git, branch master:
https://git.openwrt.org/e40a281b067f354d608f7ce01c9f7ff76b48b6aa

commit e40a281b067f354d608f7ce01c9f7ff76b48b6aa
Author: Petr Štetiar <ynezz at true.cz>
AuthorDate: Mon May 15 09:12:16 2023 +0200

    Bump buildbot version to latest stable release 3.8.0
    
    Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 .github/workflows/build-push.yml | 2 +-
 docker/buildmaster/Dockerfile    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/build-push.yml b/.github/workflows/build-push.yml
index 903c4b2..451fc87 100644
--- a/.github/workflows/build-push.yml
+++ b/.github/workflows/build-push.yml
@@ -8,7 +8,7 @@ on:
   pull_request:
 
 env:
-  BUILDBOT_VERSION: 3.5.0
+  BUILDBOT_VERSION: 3.8.0
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
diff --git a/docker/buildmaster/Dockerfile b/docker/buildmaster/Dockerfile
index 9e939d3..f4b3afb 100644
--- a/docker/buildmaster/Dockerfile
+++ b/docker/buildmaster/Dockerfile
@@ -30,7 +30,7 @@ RUN \
 RUN pip3 install -U pip
 RUN \
 	pip3 install \
-		"buildbot=$BUILDBOT_VERSION" \
+		"buildbot==$BUILDBOT_VERSION" \
 		"buildbot-www==$BUILDBOT_VERSION" \
 		"buildbot-waterfall-view==$BUILDBOT_VERSION" \
 		"buildbot-console-view==$BUILDBOT_VERSION" \