⬆️ Update PHP to v8.3.15-r0 (#358)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

bookstack/Dockerfile

@@ -12,23 +12,23 @@ RUN \
     apk add --no-cache \
         mariadb-client=11.4.4-r1 \
         nginx=1.26.2-r3 \
-        php83-curl=8.3.14-r0 \
-        php83-dom=8.3.14-r0 \
-        php83-fileinfo=8.3.14-r0 \
-        php83-fpm=8.3.14-r0 \
-        php83-gd=8.3.14-r0 \
-        php83-iconv=8.3.14-r0 \
-        php83-ldap=8.3.14-r0 \
-        php83-mbstring=8.3.14-r0 \
-        php83-mysqlnd=8.3.14-r0 \
-        php83-openssl=8.3.14-r0 \
-        php83-pdo_mysql=8.3.14-r0 \
-        php83-session=8.3.14-r0 \
-        php83-simplexml=8.3.14-r0 \
-        php83-tokenizer=8.3.14-r0 \
-        php83-xml=8.3.14-r0 \
-        php83-xmlwriter=8.3.14-r0 \
-        php83=8.3.14-r0 \
+        php83-curl=8.3.15-r0 \
+        php83-dom=8.3.15-r0 \
+        php83-fileinfo=8.3.15-r0 \
+        php83-fpm=8.3.15-r0 \
+        php83-gd=8.3.15-r0 \
+        php83-iconv=8.3.15-r0 \
+        php83-ldap=8.3.15-r0 \
+        php83-mbstring=8.3.15-r0 \
+        php83-mysqlnd=8.3.15-r0 \
+        php83-openssl=8.3.15-r0 \
+        php83-pdo_mysql=8.3.15-r0 \
+        php83-session=8.3.15-r0 \
+        php83-simplexml=8.3.15-r0 \
+        php83-tokenizer=8.3.15-r0 \
+        php83-xml=8.3.15-r0 \
+        php83-xmlwriter=8.3.15-r0 \
+        php83=8.3.15-r0 \
     \
     && apk add --no-cache --virtual .build-dependencies \
        composer=2.8.4-r0 \