Makefile: Pass PAGER/GIT_PAGER variable

Allow to override the PAGER/GIT_PAGER variables inside the container.
Use `cat` as pager when running in Github Actions (to avoid things like
`git diff` stalling the CI).

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

.github/workflows/test.yml

@@ -14,6 +14,8 @@ on:
 
 env:
   GO_VERSION: "1.21.7"
+  GIT_PAGER: "cat"
+  PAGER: "cat"
 
 jobs:
   validate-dco:

Makefile

@@ -16,6 +16,9 @@ export VALIDATE_REPO
 export VALIDATE_BRANCH
 export VALIDATE_ORIGIN_BRANCH
 
+export PAGER
+export GIT_PAGER
+
 # env vars passed through directly to Docker's build scripts
 # to allow things like `make KEEPBUNDLE=1 binary` easily
 # `project/PACKAGERS.md` have some limited documentation of some of these
@@ -77,6 +80,8 @@ DOCKER_ENVS := \
 	-e DEFAULT_PRODUCT_LICENSE \
 	-e PRODUCT \
 	-e PACKAGER_NAME \
+	-e PAGER \
+	-e GIT_PAGER \
 	-e OTEL_EXPORTER_OTLP_ENDPOINT \
 	-e OTEL_EXPORTER_OTLP_PROTOCOL \
 	-e OTEL_SERVICE_NAME