fix: populate release cache on 'show' for non-installed packages

Since #1419, get_github_releases, get_gitlab_releases, and get_website
only refresh their cache files for 'install', 'fix-installed', or
'update' (the latter only when the package is installed). As a result,
'deb-get show <pkg>' on a non-installed package that uses one of those
sources prints empty Published and Download lines — the per-package
script reads the cache to derive URL and VERSION_PUBLISHED, but the
cache was never fetched.

Adding 'show' to the action allowlist keeps the 'no cache for apps we
never install' intent in place (no change for list/prettylist/etc) while
making sure 'show' returns a complete record for any supported package.

Closes #1842

Author: mvanhorn

deb-get

@@ -180,7 +180,7 @@ function get_github_releases() {
     #   curl -I https://api.github.com/users/flexiondotorg
 
     # Do not process github releases while generating a pretty list or upgrading
-    if [[ ' install fix-installed ' =~ " ${ACTION} " ]] || { [[ ' update ' =~ " ${ACTION} " ]] && package_is_installed "${APP}"; }; then
+    if [[ ' install fix-installed show ' =~ " ${ACTION} " ]] || { [[ ' update ' =~ " ${ACTION} " ]] && package_is_installed "${APP}"; }; then
         if [ ! -e "${CACHE_FILE}" ] || [ -n "$(find "${CACHE_FILE}" -mmin +"${DEBGET_CACHE_RTN:-60}")" ]; then
             if [ -z ${QUIET} ]; then
                 fancy_message info "Updating ${CACHE_FILE}"
@@ -210,7 +210,7 @@ function get_gitlab_releases() {
     # So for gitlab sourced apps that use this release model users can use 99-local to pin a version
     #
 
-    if [[ ' install fix-installed ' =~ " ${ACTION} " ]] || { [[ ' update ' =~ " ${ACTION} " ]] && package_is_installed "${APP}"; }; then
+    if [[ ' install fix-installed show ' =~ " ${ACTION} " ]] || { [[ ' update ' =~ " ${ACTION} " ]] && package_is_installed "${APP}"; }; then
         if [ ! -e "${CACHE_FILE}" ] || [ -n "$(find "${CACHE_FILE}" -mmin +"${DEBGET_CACHE_RTN:-60}")" ]; then
             if [ -z ${QUIET} ]; then
                 fancy_message info "Updating ${CACHE_FILE}"
@@ -239,7 +239,7 @@ function get_gitlab_releases() {
 function get_website() {
     METHOD="website"
     CACHE_FILE="${CACHE_DIR}/${APP}.html"
-    if [[ ' install fix-installed ' =~ " ${ACTION} " ]] || { [[ ' update ' =~ " ${ACTION} " ]] && package_is_installed "${APP}"; }; then
+    if [[ ' install fix-installed show ' =~ " ${ACTION} " ]] || { [[ ' update ' =~ " ${ACTION} " ]] && package_is_installed "${APP}"; }; then
         if [ ! -e "${CACHE_FILE}" ] || [ -n "$(find "${CACHE_FILE}" -mmin +"${DEBGET_CACHE_RTN:-60}")" ]; then
             if [ -z ${QUIET} ]; then
                 fancy_message info "Updating ${CACHE_FILE}"