GHA: main-wasm.yml: build with stable Tcl core-9-0-\d+ releases

Filter out unwanted tag version as candiates to build with:

refs/tags/core-9-0-b3 UNWANTED
refs/tags/core-9-0-b2 UNWANTED
refs/tags/core-9-0-b1-rc4 UNWANTED
refs/tags/core-9-0-b1 UNWANTED
refs/tags/core-9-0-a3 UNWANTED
refs/tags/core-9-0-a1 UNWANTED
refs/tags/core-9-0-4
refs/tags/core-9-0-3
refs/tags/core-9-0-2
refs/tags/core-9-0-1
refs/tags/core-9-0-0

Previously the lexical order would result in alpha/beta/rc
matching in preference to the stable Tcl version IDs.  So our WASM
build would not be against the upstream stable release which is
the intention.

.github/workflows/main-wasm.yml

@@ -94,6 +94,8 @@ jobs:
             TCL_REF=$(git ls-remote --tags --sort=-version:refname "$TCL_REPO_URL" \
                         'refs/tags/core-9-0-*' \
                       | grep -v '\^{}' \
+                      | grep -P "core-.*?-\d+$" \
+                      | sort -k +2 -r -V \
                       | head -1 \
                       | awk '{print $2}' \
                       | sed 's|refs/tags/||')