ci: fix pre-commit scripts compatibility with posix shells (#4243)

Co-authored-by: James Elliott <james-d-elliott@users.noreply.github.com>

.github/pre-commit

@@ -1,7 +1,6 @@
 #!/bin/sh
 
-if [[ ! -z "$NO_HOOK" ]]
-then
+if [ -n "$NO_HOOK" ]; then
   exit 0
 fi
 
@@ -9,4 +8,4 @@ fi
 . "$(dirname "$0")/required-apps"
 
 golangci-lint run -v --fix && \
-cd web && ${PMGR} lint
+cd web && "${PMGR}" lint

.github/required-apps

@@ -1,17 +1,17 @@
 #!/bin/sh
 
-PMGR=pnpm
+export PMGR=pnpm
 
-if [[ ! -x "$(command -v golangci-lint)" ]]; then
+if [ ! -x "$(command -v golangci-lint)" ]; then
   echo "You must install golangci-lint."
   exit 1
 fi
 
-if [[ ! -x "$(command -v pnpm)" ]]; then
-  PMGR=yarn
-  if [[ ! -x "$(command -v yarn)" ]]; then
-    PMGR=npm
-    if [[ ! -x "$(command -v npm)" ]]; then
+if [ ! -x "$(command -v pnpm)" ]; then
+  export PMGR=yarn
+  if [ ! -x "$(command -v yarn)" ]; then
+    export PMGR=npm
+    if [ ! -x "$(command -v npm)" ]; then
       echo "You must install a node package manager."
       exit 1
     fi