Bump external/bpftool from `3aea563` to `a7f0e7f` (#830)

* Bump external/bpftool from `3aea563` to `a7f0e7f`

Bumps [external/bpftool](https://github.com/dthaler/bpftool-1) from `3aea563` to `a7f0e7f`.
- [Release notes](https://github.com/dthaler/bpftool-1/releases)
- [Commits](3aea5630b1...a7f0e7f057)

---
updated-dependencies:
- dependency-name: external/bpftool
  dependency-type: direct:production
...

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

* Fix gitmodules to point to windows branch

Signed-off-by: Dave Thaler <dthaler@microsoft.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Dave Thaler <dthaler@microsoft.com>
Co-authored-by: Alan Jowett <alanjo@microsoft.com>

.gitmodules

@@ -9,6 +9,7 @@
 [submodule "external/bpftool"]
 	path = external/bpftool
 	url = https://github.com/dthaler/bpftool-1.git
+	branch = windows
 [submodule "external/win-c"]
 	path = external/win-c
 	url = https://github.com/takamin/win-c.git