chore(deps): bump virtualenv from 20.16.7 to 20.26.6 in /.kokoro (#413)

Bumps [virtualenv](https://github.com/pypa/virtualenv) from 20.16.7 to 20.26.6.
- [Release notes](https://github.com/pypa/virtualenv/releases)
- [Changelog](https://github.com/pypa/virtualenv/blob/main/docs/changelog.rst)
- [Commits](pypa/virtualenv@20.16.7...20.26.6)

---
updated-dependencies:
- dependency-name: virtualenv
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.kokoro/requirements.txt

@@ -149,17 +149,17 @@ cryptography==42.0.4 \
     # via
     #   gcp-releasetool
     #   secretstorage
-distlib==0.3.6 \
-    --hash=sha256:14bad2d9b04d3a36127ac97f30b12a19268f211063d8f8ee4f47108896e11b46 \
-    --hash=sha256:f35c4b692542ca110de7ef0bea44d73981caeb34ca0b9b6b2e6d7790dda8f80e
+distlib==0.3.9 \
+    --hash=sha256:47f8c22fd27c27e25a65601af709b38e4f0a45ea4fc2e710f65755fa8caaaf87 \
+    --hash=sha256:a60f20dea646b8a33f3e7772f74dc0b2d0772d2837ee1342a00645c81edf9403
     # via virtualenv
 docutils==0.19 \
     --hash=sha256:33995a6753c30b7f577febfc2c50411fec6aac7f7ffeb7c4cfe5991072dcf9e6 \
     --hash=sha256:5e1de4d849fee02c63b040a4a3fd567f4ab104defd8a5511fbbc24a8a017efbc
     # via readme-renderer
-filelock==3.8.0 \
-    --hash=sha256:55447caa666f2198c5b6b13a26d2084d26fa5b115c00d065664b2124680c4edc \
-    --hash=sha256:617eb4e5eedc82fc5f47b6d61e4d11cb837c56cb4544e39081099fa17ad109d4
+filelock==3.16.1 \
+    --hash=sha256:2082e5703d51fbf98ea75855d9d5527e33d8ff23099bec374a134febee6946b0 \
+    --hash=sha256:c249fbfcd5db47e5e2d6d62198e565475ee65e4831e2561c8e313fa7eb961435
     # via virtualenv
 gcp-docuploader==0.6.4 \
     --hash=sha256:01486419e24633af78fd0167db74a2763974765ee8078ca6eb6964d0ebd388af \
@@ -360,9 +360,9 @@ pkginfo==1.8.3 \
     --hash=sha256:848865108ec99d4901b2f7e84058b6e7660aae8ae10164e015a6dcf5b242a594 \
     --hash=sha256:a84da4318dd86f870a9447a8c98340aa06216bfc6f2b7bdc4b8766984ae1867c
     # via twine
-platformdirs==2.5.4 \
-    --hash=sha256:1006647646d80f16130f052404c6b901e80ee4ed6bef6792e1f238a8969106f7 \
-    --hash=sha256:af0276409f9a02373d540bf8480021a048711d572745aef4b7842dad245eba10
+platformdirs==4.3.6 \
+    --hash=sha256:357fb2acbc885b0419afd3ce3ed34564c13c9b95c89360cd9563f73aa5e2b907 \
+    --hash=sha256:73e575e1408ab8103900836b97580d5307456908a03e92031bab39e4554cc3fb
     # via virtualenv
 protobuf==3.20.3 \
     --hash=sha256:03038ac1cfbc41aa21f6afcbcd357281d7521b4157926f30ebecc8d4ea59dcb7 \
@@ -482,9 +482,9 @@ urllib3==1.26.19 \
     # via
     #   requests
     #   twine
-virtualenv==20.16.7 \
-    --hash=sha256:8691e3ff9387f743e00f6bb20f70121f5e4f596cae754531f2b3b3a1b1ac696e \
-    --hash=sha256:efd66b00386fdb7dbe4822d172303f40cd05e50e01740b19ea42425cbe653e29
+virtualenv==20.26.6 \
+    --hash=sha256:280aede09a2a5c317e409a00102e7077c6432c5a38f0ef938e643805a7ad2c48 \
+    --hash=sha256:7345cc5b25405607a624d8418154577459c3e0277f5466dd79c49d5e492995f2
     # via nox
 webencodings==0.5.1 \
     --hash=sha256:a0af1213f3c2226497a97e2b3aa01a7e4bee4f403f95be16fc9acd2947514a78 \