Fix calcualtion of previous tag for release note generation

We used to generate release notes after tagging, so it was possible to just
list the tags and pick the one before the current. This is no longer the case.
Now we need to add the upcoming tag to the list since we generate the release
notes before creating the tag.

Signed-off-by: Lennart Jern <[email protected]>

Author: lentzi90

Makefile

@@ -452,7 +452,8 @@ staging-manifests:
 ifneq (,$(findstring -,$(RELEASE_TAG)))
     PRE_RELEASE=true
 endif
-PREVIOUS_TAG ?= $(shell git tag -l | grep -E "^v[0-9]+\.[0-9]+\.[0-9]+$$" | sort -V | grep -B1 $(RELEASE_TAG) | head -n 1 2>/dev/null)
+# List all tags, add the new tag to the list, sort and pick the previous one.
+PREVIOUS_TAG ?= $(shell (git tag -l | grep -E "^v[0-9]+\.[0-9]+\.[0-9]+$$"; echo "$(RELEASE_TAG)") | sort -V | grep -B1 "^$(RELEASE_TAG)$$" | grep -v "^$(RELEASE_TAG)$$" | head -n 1 2>/dev/null)
 ## set by Prow, ref name of the base branch, e.g., main
 RELEASE_DIR := out
 RELEASE_NOTES_DIR := releasenotes