Talisman scan brings to OOM on large repository

[mefistofeel]

Describe the bug
I have a large Repo (607.7 MiB /.git), if I run a Talisman scan on this repo, it's exit with code 2 and following error:

`14:24:12 fatal error: runtime: out of memory

14:24:12 runtime stack:

14:24:12 runtime.throw(0x8b562a, 0x16)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/panic.go:774 +0x72

14:24:12 runtime.sysMap(0xc0c0000000, 0x4000000, 0xed93f8)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/mem_linux.go:169+0xc5

14:24:12 runtime.(*mheap).sysAlloc(0xec0f80, 0xd50000, 0x79f380, 0x1280023b177)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/malloc.go:701 +0x1cd

14:24:12 runtime.(*mheap).grow(0xec0f80, 0x6a8, 0xffffffff)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/mheap.go:1255 +0xa3

14:24:12 runtime.(*mheap).allocSpanLocked(0xec0f80, 0x6a8, 0xed9408, 0x41f495)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/mheap.go:1170 +0x266

14:24:12 runtime.(*mheap).alloc_m(0xec0f80, 0x6a8, 0x7f4256a20101, 0x7f4256a2d918)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/mheap.go:1022 +0xc2

14:24:12 runtime.(*mheap).alloc.func1()

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/mheap.go:1093 +0x4c

14:24:12 runtime.(*mheap).alloc(0xec0f80, 0x6a8, 0x7f4284010101, 0x7f42842543a8)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/mheap.go:1092 +0x8a

14:24:12 runtime.largeAlloc(0xd4e6fe, 0x830101, 0x833380)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/malloc.go:1138 +0x97

14:24:12 runtime.mallocgc.func1()

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/malloc.go:1033 +0x46

14:24:12 runtime.systemstack(0x0)

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/asm_amd64.s:370 +0x66

14:24:12 runtime.mstart()

14:24:12 /home/travis/.gimme/versions/go1.13.4.linux.amd64/src/runtime/proc.go:1146`

Machine on which I run a scan have 4*3.2GHz and 8Gb of RAM.

[mefistofeel]

as a workaround I have changed git option at scanner.go

talisman/scanner/scanner.go

Line 66 in 5867a0f

out, err := exec.Command("git", "log", "--all", "--pretty=%H").CombinedOutput()

from "--all" to "--max-count=10", its scan only last 10 commits.