tools/ci: sanitize Docker tags

Sanitize Docker tags to remove characters used in semver that are not
valid in Docker tags (primarily `+`)

tools/ci/docker-containers

@@ -44,6 +44,8 @@ else
   VERSION=$(./tools/image-tag)
 fi
 
+SANITIZED_VERSION=$(echo $VERSION | sed 's/+/-/g')
+
 # We also need to know which "branch tag" to update. Branch tags are used as a
 # secondary tag for Docker containers. The branch tag is "latest" when being
 # tagged from a stable release (i.e., not a release candidate).
@@ -54,7 +56,7 @@ fi
 if [ -n "$DRONE_TAG" ] && [[ "$DRONE_TAG" != *"-rc."* ]]; then
   BRANCH_TAG=latest
 else
-  BRANCH_TAG=$VERSION
+  BRANCH_TAG=$SANITIZED_VERSION
 fi
 
 # Build all of our images.
@@ -68,7 +70,7 @@ case "$TARGET_CONTAINER" in
       --platform $BUILD_PLATFORMS     \
       --build-arg RELEASE_BUILD=1     \
       --build-arg VERSION="$VERSION"  \
-      -t "$AGENT_IMAGE:$VERSION"      \
+      -t "$AGENT_IMAGE:$SANITIZED_VERSION"  \
       -t "$AGENT_IMAGE:$BRANCH_TAG"   \
       -f cmd/grafana-agent/Dockerfile \
       .
@@ -80,7 +82,7 @@ case "$TARGET_CONTAINER" in
       --build-arg RELEASE_BUILD=1     \
       --build-arg VERSION="$VERSION"  \
       --build-arg GOEXPERIMENT=boringcrypto \
-      -t "$AGENT_BORINGCRYPTO_IMAGE:$VERSION"      \
+      -t "$AGENT_BORINGCRYPTO_IMAGE:$SANITIZED_VERSION"      \
       -t "$AGENT_BORINGCRYPTO_IMAGE:$BRANCH_TAG"   \
       -f cmd/grafana-agent/Dockerfile \
       .