Bump stringstream from 0.0.5 to 0.0.6 in /css

Bumps [stringstream](https://github.com/mhart/StringStream) from 0.0.5 to 0.0.6.
- [Release notes](https://github.com/mhart/StringStream/releases)
- [Commits](https://github.com/mhart/StringStream/compare/v0.0.5...v0.0.6)

Signed-off-by: dependabot[bot] <support@github.com>

css/package-lock.json

@@ -88,6 +88,7 @@
             "version": "2.10.1",
             "resolved": "https://registry.npmjs.org/boom/-/boom-2.10.1.tgz",
             "integrity": "sha1-OciRjO/1eZ+D+UkqhI9iWt0Mdm8=",
+            "optional": true,
             "requires": {
                 "hoek": "2.x.x"
             }
@@ -141,6 +142,7 @@
             "version": "1.0.6",
             "resolved": "https://registry.npmjs.org/combined-stream/-/combined-stream-1.0.6.tgz",
             "integrity": "sha1-cj599ugBrFYTETp+RFqbactjKBg=",
+            "optional": true,
             "requires": {
                 "delayed-stream": "~1.0.0"
             }
@@ -227,7 +229,8 @@
         "delayed-stream": {
             "version": "1.0.0",
             "resolved": "https://registry.npmjs.org/delayed-stream/-/delayed-stream-1.0.0.tgz",
-            "integrity": "sha1-3zrhmayt+31ECqrgsp4icrJOxhk="
+            "integrity": "sha1-3zrhmayt+31ECqrgsp4icrJOxhk=",
+            "optional": true
         },
         "depd": {
             "version": "1.1.2",
@@ -296,7 +299,8 @@
         "extsprintf": {
             "version": "1.3.0",
             "resolved": "https://registry.npmjs.org/extsprintf/-/extsprintf-1.3.0.tgz",
-            "integrity": "sha1-lpGEQOMEGnpBT4xS48V06zw+HgU="
+            "integrity": "sha1-lpGEQOMEGnpBT4xS48V06zw+HgU=",
+            "optional": true
         },
         "finalhandler": {
             "version": "1.1.0",
@@ -452,7 +456,8 @@
         "hoek": {
             "version": "2.16.3",
             "resolved": "https://registry.npmjs.org/hoek/-/hoek-2.16.3.tgz",
-            "integrity": "sha1-ILt0A9POo5jpHcRxCo/xuCdKJe0="
+            "integrity": "sha1-ILt0A9POo5jpHcRxCo/xuCdKJe0=",
+            "optional": true
         },
         "hpack.js": {
             "version": "2.1.6",
@@ -663,12 +668,14 @@
         "mime-db": {
             "version": "1.33.0",
             "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.33.0.tgz",
-            "integrity": "sha512-BHJ/EKruNIqJf/QahvxwQZXKygOQ256myeN/Ew+THcAa5q+PjyTTMMeNQC4DZw5AwfvelsUrA6B67NKMqXDbzQ=="
+            "integrity": "sha512-BHJ/EKruNIqJf/QahvxwQZXKygOQ256myeN/Ew+THcAa5q+PjyTTMMeNQC4DZw5AwfvelsUrA6B67NKMqXDbzQ==",
+            "optional": true
         },
         "mime-types": {
             "version": "2.1.18",
             "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.18.tgz",
             "integrity": "sha512-lc/aahn+t4/SWV/qcmumYjymLsWfN3ELhpmVuUFjgsORruuZPVSwAQryq+HHGvO/SI2KVX26bx+En+zhM8g8hQ==",
+            "optional": true,
             "requires": {
                 "mime-db": "~1.33.0"
             }
@@ -1010,9 +1017,9 @@
             }
         },
         "stringstream": {
-            "version": "0.0.5",
+            "version": "0.0.6",
-            "resolved": "https://registry.npmjs.org/stringstream/-/stringstream-0.0.5.tgz",
+            "resolved": "https://registry.npmjs.org/stringstream/-/stringstream-0.0.6.tgz",
-            "integrity": "sha1-TkhM1N5aC7vuGORjB3EKioFiGHg=",
+            "integrity": "sha512-87GEBAkegbBcweToUrdzf3eLhWNg06FJTebl4BVJz/JgWy8CvEr9dRtX5qWphiynMSQlxxi+QqN0z5T32SLlhA==",
             "optional": true
         },
         "strip-json-comments": {