Update Jerboa toolchain to v0.2.8

ober

49c0aa56e5c82c2cbe1a899eeefa7ba4484088d0

diff --git a/Makefile b/Makefile
index efc0948..2efe514 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-JERBOA_VERSION ?= v0.2.3
+JERBOA_VERSION ?= v0.2.8
 JERBOA_TOOL_DIR ?= $(CURDIR)/.jerboa/bin
 JERBUILD ?= $(shell if [ -x "$(CURDIR)/../jerboa/dist/jerbuild" ]; then printf '%s\n' "$(CURDIR)/../jerboa/dist/jerbuild"; elif command -v jerbuild >/dev/null 2>&1; then command -v jerbuild; else printf '%s\n' "$(JERBOA_TOOL_DIR)/jerbuild"; fi)
 JERBUILD_ABS = $(abspath $(JERBUILD))