bashlog: add back bash3.2 compatible uppercase

For now the perf issue of the shim is solved, so it's fine for debug
logging to be of lower performance.

Author: reegnz

lib/bashlog.sh

@@ -32,7 +32,7 @@ function log() {
   local pid="${$}";
 
   local level="${1}";
-  local upper="${level^^}";
+  local upper="$(tr '[:lower:]' '[:upper:]')";
   local debug_level="${TFENV_DEBUG:-0}";
   local stdout_colours="${BASHLOG_COLOURS:-1}";